Chemotherapy and radiotherapy:Could they contribute to the development of new tumors and metastases?

Objective: Both chemotherapy and radiotherapy have demonstrated high effectiveness as the best mechanisms in the fight against cancer;however, various studies seem to confirm that they could also favor the development of other unwanted effects of great importance for the patient. The main objective of this study is to find out the possible existence of this type of links. Method: This is a systematic literature review that seeks to find out which and how long cases of late interactions related to chemotherapy and radiotherapy treatments have been known. The bibliographic review was carried out based on references published in the last five years. Results: Various studies confirm the possible relationship between chemotherapy and radiotherapy treatments with the development of new undesirable side effects, especially as a consequence of the hepatotoxicity generated in the case of chemotherapy and radiation in radiotherapy. However, in this last type of treatment, the problems raised are really few. Conclusions: The existence of a risk of suffering new unwanted side effects after different types of treatment seems to have been demonstrated, especially in the case of chemotherapy. In the case of radiotherapy, adverse effects are practically non-existent, although they are no less important.

Intensity-modulated radiation therapy with concurrent chemotherapy for locally advanced cervical and upper thoracic esophageal cancer

AIM： To evaluate the dosimetry, efficacy and toxicity of intensity-modulated radiation therapy （IMRT） and concurrent chemotherapy for patients with locally advanced cervical and upper thoracic esophageal cancer. METHODS： A retrospective study was performed on 7 patients who were definitively treated with IMRT and concurrent chemotherapy. Patients who did not receive IMRT radiation and concurrent chemotherapy were not included in this analysis. IMRT plans were evaluated to assess the tumor coverage and normal tissue avoidance. Treatment response was evaluated and toxicities were assessed. RESULTS： Five- to nine-beam IMRT were used to deliver a total dose of 59.4-66 Gy （median： 64.8 Gy） to the primary tumor with 6-MV photons. The minimum dose received by the planning tumor volume （PTV） of the gross tumor volume boost was 91.2%-98.2% of the prescription dose （standard deviation [SD]： 3.7%-5.7%）. The minimum dose received by the PTV Of the clinical tumor volume was 93.8%-104.8% （SD： 4.3%-11.1%） of the prescribed dose. With a median follow-up of 15 rno （range： 3-21 too）, all 6 evaluable patients achieved complete response. Of them, 2 developed local recurrences and 2 had distant metastases, 3 survived with no evidence of disease. After treatment, 2 patients developed esophageal stricture requiring frequent dilation and 1 patient developed tracheal-esophageal fistula. CONCLUSION： Concurrent IMRT and chemotherapy resulted in an excellent early response in patients with locally advanced cervical and upper thoracic esophageal cancer. However, local and distant recurrence and toxicity remain to be a problem. Innovative approaches are needed to improve the outcome.

Downregulation of Telomerase Activity in Breast Cancer Impairs Cells Proliferation, Invasive Ability and Sensitizes Cells to Ultraviolet-Radiation and Adriamycin-Chemotherapy <i>in Vitro</i>

Backgroud: Telomerase activity, mainly regulated by the human telomerase reverse transcriptase (hTERT) gene, plays critical roles in tumor growth and progression through the maintenance of telomere length and structure. Telomerase is elevated in most malignant tumors as well as in breast cancer, the ubiquitous expression of telomerase makes it a promising target for cancer therapy. With the goal of down regulating telomerase activity, RNA interference technology has been applied to specifically knockdown the hTERT gene expression in breast cancer cell line MCF-7 and MDA-MB- 231 and determine whether h TERT-specific RNA interference technology serve as an effective method of telomerase-based cancer therapy. Methods: Interfering p Super-retro-puro-hTERT-RNA and the control were transfected into breast cancer cell line MCF-7 and MDA-MB-231. The telomerase activity, cell proliferation, invasive ability and cell response to ultraviolet-radiation or adriamycin-chemotherapy in vitro were recorded in transfected, untransfeced and empty-transfected cells respectively. Results: Telomerase activity was successfully suppressed in transfected cells (P 0.005). Decreased expression of telomerase activity was associated with reduced cell proliferation (P 0.001), migration and invasive ability (P 0.001) and enhanced sensitivity to ultraviolet-radiation or adriamycin-chemotherapy (P 0.001). Conclusions: Telomerase activity down regulation inhibits breast cancer cell growth, impairs cell migration, invasion and sensitizes cancer cells to radiotherapy and chemotherapy. The hTERT-specific RNA interference technology combined with radio-therapy and/or chemotherapy may serve as an effective method of telomerase-based therapy in breast cancer.

Effects of radiation and chemotherapy on adipose stem cells: Implications for use in fat grafting in cancer patients

Autologous fat transplantation is a versatile tool in reconstructive surgery.Adipose-derived stem cells(ASCs)increase survival of fat grafts and thus are increasingly used for breast reconstruction in breast cancer patients.However,radiation and/or chemotherapy have been proposed to inhibit soft tissue regeneration in wound healing thus suggesting alteration in stem cell pathways.Therefore,elucidating effects of radiation and chemotherapy on ASCs is critical if one desires to enhance the survival of fat grafts in patients.This review outlines our work evaluating the function and recoverability of ASCs from radiation or chemotherapy patients,focusing specifically on their availability as a source of autologous stem cells for fat grafting and breast reconstruction in cancer patients.Even though evidence suggests radiation and chemotherapy negatively influence ASCs at the cellular level,the efficiency of the isolation and differentiation capacity did not appear influenced in patients after receiving chemotherapy treatment,although fat from radiated patients exhibited significantly altered ASC differentiation into endothelial-like cells.Further,the in vitro growth rates of patient’s ASCs do not differ significantly before or after treatment.Taken together,these studies suggest ASCs as an important new tool for grafting and reconstruction even when radiation and chemotherapy treatment are involved.

Clinical study on concurrent and sequential therapy of intensity modulated radiation therapy (IMRT) combined with NP regimen chemotherapy in the treatment of middle and advanced non-small cell lung cancer

Objective: To evaluate the clinical effects of concurrent and sequential therapy for middle and advanced stage non-small cell lung cancer (NSCLC) useing IMRT combined with NP regimen chemotherapy. Methods: Eighty patients with middle and advanced stage NSCLC were randomized into two groups. Forty patients were underwent sequential therapy and other 40 patients were underwent concurrent therapy. IMRT was used in radiotherapy and NP regimen of vinorelbine+cispatin (NP) was used in chemotherapy. Results: (1) The overall response (CR+PR) rate was 75% in concurrent group and 45% in sequential group (P<0.05); (2) The treatment courses were 84 days and 140 days for concurrent group and sequential group respectively (P<0.05); (3) One-year survival rate in concurrent group was 72.4% and 52.3% in sequential group respectively; (4) The toxic effects can be tolerable by all of patients. Conclusion: The concurrent chemo-radiotherapy has better overall re- sponse, one-year survival rate and shorter treatment course than the sequential chemo-radiotherapy, so it is a better method for the treatment of middle and advanced stage NSCLC, but the long term survival rate will be studied.

Clinical Effect of Biafine in Preventing and Treating Radioactive Skin Destruction of Nasopharyngeal Carcinoma Patients Caused by Concurrent Intensity- Modulated Radiotherapy and Chemotherapy

OBJECTIVE To observe the clinical effect of Biafine cream in preventing and treating radioactive skin destruction of nasopharyngeal carcinoma （NPC） patients induced by synchronized intensity-modulated radiotherapy and chemotherapy. METHODS The patients were treated with Varian-600CD 6 MV X-ray three-dimensional （3D） conformal intensity-modulation radiotherapy （IMRT）, with a 120-blade multiple leaf-blade grating and in combination with synchronal Capecitabine chemotherapy. Fifty-one patients undergoing radiotherapy and chemotherapy were randomized into 2 groups： 25 in the treatment group received a Biafine cream application following the first radiotherapy and / or chemotherapy, while the other 26, served as controls. They received no application of the cream, but only followed normal procedures for conventional radiotherapy and health education. RESULTS The rate of the skin-reaction was 100% in the patients of both groups. A mild radiation reaction （grade-Ⅰ and Ⅱ） occurred as follows： 88.0% （22/25 cases） in the treatment group and 57.7% （15/26 cases） in the control group. A grade-Ⅲ radiation reaction developed in 12.0% （3/25 cases） in the treatment group, and 42.3% （11/26 cases） in the controls. There was a significant difference, P〈0.01 between the two groups. Concerning the degree of the skin response before the patients received a dose of 40 Gy, the radiation reaction emerged in 32.0% （8/25） of the cases in the treatment group, and in 96.2% （25/26） of the cases of the control group. CONCLUSION Biafine cream can effectively reduce the acute irradiation or chemotherapy-induced dermal injury. It can alleviate the patients＇ suffering, improve their quality of life, and can ensure less injurious radiotherapy.

Treatment of Interstitial Peumopathy by Fei Tong Oral Liquid in the Malignant Tumor Patients after Radio-and/or Chemotherapy

Fei Tong Kou Fu Ye (肺通口服液 Fei Tong Oral Liquid) was used to treat 30 cases of interstitial pneumopathy after radio- and/or chemotherapy.In comparison with the control group (15 cases) treated with hormones,the therapeutic effects in improving dyspnea,cough,respiratory rate,cyanosis,findings in X-films and CT examination,partial pressure of oxygen in artery,FVC and VC were found significantly better (P<0.05).The total effective rate obtained was 83.33%.

Randomized phase Ⅱ trial of selenomethionine as a modulator of efficacy and toxicity of chemoradiation in squamous cell carcinoma of the head and neck

AIM: To investigate whether selenomethionine(SLM) reduces mucositis incidence in patients with head and neck squamous cell cancer(HNSCC) undergoing concurrent chemoradiation(CRT).METHODS: In this multi-institutional, randomized, double-blind phase Ⅱ trial, patients with Stage Ⅲ or Ⅳ HNSCC received SLM 3600 μg/m2 or placebo twice daily for 7 d prior to CRT, once daily during CRT, and daily for 3 wk following CRT. CRT consisted of 70 Gy at 2 Gy per fraction with cisplatin 100 mg/m2 Ⅳ on days 1, 22, and 43. RESULTS: Eighteen patients were randomized, 10 received SLM, and there were no differences in baseline factors. There was no difference in mucositis or patientreported side effects between groups. There was no difference in overall or relapse-free survival at 12 mo.CONCLUSION: Addition of SLM to CRT for HNSCC was well-tolerated but did not lower the incidence of severe mucositis or improve quality of life or survival outcomes.

Effect of intensity modulated radiation therapy combined with paclitaxel+ endostar chemotherapy on serum malignant molecule levels in patients with locally advanced non-small cell lung cancer

Objective: To discuss the effect of intensity modulated radiation therapy combined with paclitaxel + endostar chemotherapy on serum malignant molecule levels in patients with locally advanced non-small cell lung cancer. Methods: Patients with locally advanced NSCLC who were treated in the hospital between February 2015 and January 2017 were collected and divided into control group (n=59) and research group (n=59) by random number table. Control group received the routine paclitaxel + endostar chemotherapy after the operation, and research group underwent intensity modulated radiation therapy combined with paclitaxel +endostar chemotherapy after the operation. The differences in serum levels of NSCLC-related tumor markers and angiogenesis indexes were compared between the two groups before and after treatment. Results: Before treatment, the differences in serum levels of NSCLC-related tumor markers and angiogenesis indexes were not statistically significant between the two groups. After treatment, serum TK1, CYFRA21-1, Pro-GRP, CEA, CA125 and SCC-Ag levels of research group were lower than those of control group;serum EGFR, COX-2, VEGF, HIF-1 and MMP-2 levels of research group were lower than those of control group. Conclusion:Postoperative intensity modulated radiation therapy combined with paclitaxel + endostar chemotherapy can effectively reduce the serum malignant molecule levels and optimize the illness in patients with local advanced NSCLC.

Radiotherapy and Chemotherapy in T2N0 Glottic Cancer: Does Chemotherapy Improve Local Control?

Purpose: To compare concurrent chemoradiotherapy with radiotherapy in T2N0 glottic cancer. Materials and Methods: Thirty nine patients were treated with radiotherapy alone. In detail, 30 patients treated between 1985 and 1995, and 9 patients treated between 1995 and 2010 were included in the radiotherapy alone group. Between 1995 and 2010, 22 patients were treated with concurrent chemoradiotherapy. Conventional fractionation was applied in 19 patients in the radiotherapy group and in 1 patient in the chemoradiotherapy group. Hyperfractionation was applied to 20 patients in the radiotherapy group and to 21 patients in the chemoradiotherapy group. Total dose ranged from 64 Gy to 76.8 Gy in the radiotherapy group and from 66 Gy to 76.8 Gy in the chemoradiotherapy group. Cisplatin or carboplatin was administered in the chemoradiotherapy group. Results: There were no differences in the 5-year preservation rate of vocal function (82.8% vs 87.4%, p = 0.652), local control rate (77.2% vs 92.9%, p = 0.163), and 5-year overall survival rate (86.4% vs 90.2%, p = 0.497) between the radiotherapy and chemoradiotherapy groups. Conclusion: In T2N0 glottic cancer, no difference was observed between radiotherapy alone and concurrent chemoradiotherapy groups.

Low Grade Fibromyxoid Sarcomas and Multiple Myeloma in the Same Patient： One Case Report and Literature Review

IntroductionMultiple myeloma （MM） is a neoplastic plasma cell dyscrasia char-acterized by anemia; a monoclonal protein（M-protein） in the serum and/or urine; abnormal bone radiographs and bone pain;hypercal-cemia; and renal insuf.ciency or failure.According to the results of immunoelectrophoresis, patients are separated to Ig type （IgG, IgA, IgD, IgE and IgM）; light chain; nonsecretory.

The Effect of Photon Flux Density and Lighting Period on Growth,Flowering,Powdery Mildew and Water Relations of Miniature Roses

Miniature roses (Rosa sp.) were grown at 100 and 150 μmol m-2·s-1 photon flux densities (PFD) with 16, 20 and 24 h·day-1 lighting periods (LP) in a greenhouse compartment in midwinter at latitude 59° north. The study included 10 different treatments and six rose cultivars, altogether 900 plants. The 16 and 20 h LP were applied with or without a dark period of 8 and 4 h·day-1, respectively, by timing the LP in relation to daylight that lasted for 7 - 8 h. Number of days until flowering decreased with an increase in PFD and in LP up to 24 day-1 and was unaffected by the timing of the 16 and 20 h·day-1 LP. Number of flowers and plant dry weight increased 20% to 30% by increasing the PFD. Plant dry weight increased by increasing the LP from 16 to 20 h·day-1 (about 25%), but no effect was found with a further increase to 24 h·day-1. Mean growth rate until flowering increased 30% to 40% by increasing the PFD or by increasing the LP from 16 to 20 h day-1, while little effect was found by a further increase to 24 h·day-1. Increasing the photosynthetic active radiation (PAR) by increasing the LP from 16 to 20 h·day-1 increased the growth rate more than increasing the PFD did. Three of the cultivars were tested for water loss after the detachment of some leaves. Leaves that had developed without a dark period showed a considerably higher water loss than the treatments that included a dark period of 4 or 8 h·day-1. The keeping quality at indoor conditions, however, was unaffected by the treatment due to sufficient watering. Powdery mildew developed significantly more on plants grown with a dark period of 8 h as compared with the other treatments. It was concluded that 20 h·day-1 LP including a dark period of 4 h·day-1 and a PFD of at least 150 μmol·m-2·s-1 should be applied to miniature roses during the winter months in order to effectively produce miniature pot roses with a high quality.

Effect of Docetaxel and Cisplatin Chemotherapy Combined with Intensitymodulated Radiotherapy in the Treatment of Postoperative Recurrence of Esophageal Cancer and Its Effect on Serum Tumor Markers

Objective: To investigate the effect of docetaxel and cisplatin combined with intensity-modulated radiotherapy in thetreatment of postoperative recurrence of esophageal cancer and the content of tumor markers in serum. Methods: According tosimple randomization method, 60 patients with postoperative recurrence of esophageal cancer admitted from February 2018 toSeptember 2019 were divided into control group (n = 30 cases) and observation group (n = 30 cases). All patients received IMRT.Fluorouracil + cisplatin was used in the control group and docetaxel + cisplatin was used in the observation group. After 2 coursesof continuous treatment, the therapeutic effect, serum tumor marker content and adverse reactions were compared between thetwo groups. Results: After treatment, the effective rate of observation group was higher than control group, and the difference wasstatistically significant (P < 0.05).The contents of carcinoembryonic antigen (CEA), squamous cell carcinoma antigen (SCC) andcarbohydrate antigen 19-9 (CA19-9) in observation group were lower than those in control group, and the difference was statisticallysignificant (P < 0.05). The incidence of adverse reactions in the observation group was lower than that in the control group, and thedifference was statistically significant (P < 0.05). Conclusion: Docetaxel and cisplatin combined with intensemodulated radiotherapyfor postoperative recurrence of esophageal cancer can improve the therapeutic effect, inhibit the malignant degree of tumor, andreduce the incidence of adverse reactions.

Postoperative complications and critical care management after cytoreduction surgery and hyperthermic intraperitoneal chemotherapy: A systematic review of the literature

BACKGROUND Cytoreductive surgery(CRS)and hyperthermic intraperitoneal chemotherapy(HIPEC)is a comprehensive treatment option performed for peritoneal surface malignancies.Postoperatively almost all patients are transferred to the intensive care unit electively.AIM To describe the common and rare postoperative complications,postoperative mortality and their critical care management after CRS-HIPEC.METHODS The authors assessed 54 articles for eligibility.Full text assessment identified 14 original articles regarding postoperative complications and critical care management for inclusion into the final review article.RESULTS There is an exaggerated metabolic and inflammatory response after surgery which may be termed as physiological in view of the nature of surgery combined with the use of heated intraperitoneal chemotherapy with/out early postoperative intravenous chemotherapy.The expected postoperative course is further discussed.CRS-HIPEC is a complex procedure with some life-threatening complications in the immediate postoperative period,reported morbidity rates between 12%-60%and a mortality rate of 0.9%-5.8%.Over the years,since its inception in the 1980s,postoperative morbidity and survival have significantly improved.The commonest postoperative surgical complications and systemic toxicity due to chemotherapy as reported in the last decade are discussed.CONCLUSION CRS-HIPEC is associated with a varying rate of postoperative complications including postoperative deaths and needs early suspicion and intensive care monitoring.

Inflammatory bowel disease and cancer: The role of inflammation, immunosuppression, and cancer treatment

In patients with inflammatory bowel disease(IBD), chronic inflammation is a major risk factor for the development of gastrointestinal malignancies. The pathogenesis of colitis-associated cancer is distinct from sporadic colorectal carcinoma and the critical molecular mechanisms underlying this process have yet to be elucidated. Patients with IBD have also been shown to be at increased risk of developing extra-intestinal malignancies. Medical therapies that diminish the mucosal inflammatory response represent the foundation of treatment in IBD, and recent evidence supports their introduction earlier in the disease course. However, therapies that alter the immune system, often used for long durations, may also promote carcinogenesis. As the population of patients with IBD grows older, with longer duration of chronic inflammation and longer exposure to immunosuppression, there is an increasing risk of cancer development. Many of these patients will require cancer treatment, including chemotherapy, radiation, hormonal therapy, and surgery. Many patients will require further treatment for their IBD. This review seeks to explore the characteristics and risks of cancer in patients with IBD, and to evaluate the limited data on patients with IBD and cancer, including management of IBD after a diagnosis of cancer, the effects of cancer treatment on IBD, and the effect of IBD and medications for IBD on cancer outcomes.

Chemotherapy as a component of multimodal therapy for gastric carcinoma

Prognosis of locally advanced gastric cancer remains poor, and several multimodality strategies involving surgery, chemotherapy, and radiation have been tested in clinical trials. Phase Ⅲ trial testing the benefit of postoperative adjuvant chemotherapy over treatment with surgery alone have revealed little impact on survival, with the exception of some small trials in Western nations. A large trial from the United States exploring postoperative chemoradiation was the first major success in this category. Results from Japanese trials suggest that moderate chemotherapy with oral fluoropyrimidines may be effective against less-advanced （T2-stage） cancer, although another confirmative trial is needed to prove this point. Investigators have recently turned to neoadjuvant chemotherapy, and some promising results have been reported from phase Ⅱ trials using active drug combinations. In 2005, a large phase Ⅲ trial testing preand postoperative chemotherapy has proven its survival benefit for resectable gastric cancer. Since the rate of pathologic complete response is considered to affect treatment results of this strategy, neoadjuvant chemoradiation that further increases the incidence of pathologic complete response could be a breakthrough, and phase Ⅲ studies testing this strategy may be warranted in the near future.

Capecitabine with radiation is an effective adjuvant therapy in gastric cancers

AIM:To analyze the outcome of patients who received concurrent capecitabine(Xeloda) and radiation(XRT) compared to the established concurrent 5-fluorouracil(5-FU) with radiation(5FU-RT) and fluoropyrimidine-based chemotherapy alone as adjuvant treatment in gastric cancers.METHODS:All patients with gastric cancers who received adjuvant treatment at the National Cancer Centre Singapore between 1996 and 2006 were reviewed.Treatment outcomes of patients who received XRT were compared with those who had 5FU-RT or chemotherapy alone as adjuvant therapy for gastric cancers.RESULTS:A total of 108 patients were reviewed.Median age at diagnosis was 60.The majority of the patients(64.8%) had advanced stage Ⅲ and Ⅳ disease(with no distant metastasis).All except 4 patients had D2 gastrectomy.Twenty one patients(19.4%) had positive surgical resection margins.Thirty three patients received XRT compared with 52 who had 5FU-RT and 23 who received chemotherapy alone.For the patients in the chemotherapy-only group,all had fluoropyrimidine-based therapy,with added cisplatin in 7 patients and epirubicin in 2 patients.Median recurrence-free survival was longer for the XRT group(52 mo) compared to the 5FU-RT(35 mo) and chemotherapy-only groups(25 mo)(P=0.48).The patients in the XRT group achieved similar median overall survival(53 mo) as the 5FU-RT(54 mo) and the chemotherapy-only groups(44 mo)(P=0.5).CONCLUSION:Capecitabine with concurrent radiation was as effective as concurrent 5FU with radiation or fluoropyrimidine-based chemotherapy alone when used as adjuvant treatment in patients with gastric cancers.

Targeting head and neck tumoral stem cells： From biologicalaspects to therapeutic perspectives

Head and neck squamous cell cancer(HNSCC) is the sixth most common cancer in the world. Effective therapeutic modalities such as surgery, radiation, chemotherapy and combinations of each are used in the management of the disease. In most cases, treatment fails to obtain total cancer cure. In recent years, it appears that one of the key determinants of treatment failure may be the presence of cancer stem cells(CSCs) that escape currently available therapies. CSCs form a small portion of the total tumor burden but may play a disproportionately important role in determining outcomes. CSCs have stem features such as self-renewal, high migration capacity, drug resistance, high proliferation abilities. A large body of evidence points to the fact that CSCs are particularly resistant to radiotherapy and chemotherapy. In HNSCC, CSCs have been increasingly shown to have an integral role in tumor initiation, disease progression, metastasis and treatment resistance. In the light of such observations, the present review summarizes biological characteristics of CSCs in HNSCC, outlines targeted strategies for the successful eradication of CSCs in HNSCC including targeting the self-renewal controlling pathways, blocking epithelial mesenchymal transition, niche targeting, immunotherapy approaches and highlights the need to better understand CSCs biology for new treatments modalities.

Clinical observation of gemcitabine and concomitant three-dimensional conformal radiotherapy in the treatment of locally advanced non-small cell lung cancer

Objective： To evaluate the clinical effect of gemcitabine and concurrent three-dimensional conformal radiation therapy （3D-CRT） for locally advanced non-small cell lung cancer （NSCLC）. Methods： From April 2002 to June 2005, 38 patients with inoperable stage Ⅲ NSCLC were treated with gemcitabine and 3D-CRT simultaneously. Chemotherapy consisted of intravenously gemcitabine 350 mg/m^2 on days 1, 8, 15, 22, 29, 36.3D-CRT was delivered up to a total dose of 60-64 Gy with a 2.0 Gy dose fraction per day, 5 days per week. Results： The overall response rates of primary tumor and mediastinum metastatic node were 86.8% （33/38） and 90.6% （29/32） respectively, and 91.7% （22/24） and 78.6% （11/14） for squamous cell carcinoma and adenocarcinoma respectively. The acute side effects of patients were mostly myelosuppression, nausea, vomiting, radiation-induced esophagitis and pneumonitis （RTOG 1/11）, however, all of them were cured. Conclusion： Concurrent application of gemcitabine and 3D-CRT can improve the overall response rate for locally advanced NSCLC without aggravating the side effects.

Tracing and targeting cancer stem cells:New venture for personalized molecular cancer therapy

Tumors consist of a mixture of heterogeneous cell types. Cancer stem cells(CSCs) are a minor sub-population within the bulk cancer fraction which has been foundto reconstitute and propagate the disease and to be frequently resistant to chemotherapy, irradiation, cytotoxic drugs and probably also against immune attack. CSCs are considered as the seeds of tumor recurrence, driving force of tumorigenesis and metastases. This underlines the urgent need for innovative methods to identify and target CSCs. However, the role and existence of CSCs in therapy resistance and cancer recurrence remains a topic of intense debate. The underlying biological properties of the tumor stem cells are extremely dependent on numerous signals, and the targeted inhibition of these stem cell signaling pathways is one of the promising approaches of the new antitumor therapy approaches. This perspective review article summarizes the novel methods of tracing CSCs and discusses the hallmarks of CSC identification influenced by the microenvironment or by having imperfect detection markers. In addition, explains the known molecular mechanisms of therapy resistance in CSCs as reliable and clinically predictive markers that could enable the use of new targeted antitumor therapy in the sense of personalized medicine.