Actinic keratosis and field cancerization

While actinic keratoses(AKs) have been considered precancerous until recently for being able to turn into squamous cell carcinomas(SCCs), it is now agreed that it would be more appropriate to call them cancerous. Although not all AKs turn into SCC and some of them may even have a spontaneous regression, there is an obvious association between SCC and AK. Approximately 90% of SCs have been reported to develop from AKs and AKs are the preinvasive form of SCCs. The presence of two or more AKs on a photodamaged skin is an indicator of field cancerization and represents an increased risk of invasive SCC. All lesions should be treated since it cannot be foreseen which of the lesions will regress and which will progress to SCC. AK can be a single lesion or it can involve multiple lesions in a field of cancerization; thus, AK treatment is grouped under two headings:(1) Lesion-specific treatment; and (2) Field-targeted treatment. Lesion-specific treatments are practicable in patients with a small number of clinically visible and isolated lesions. These treatments including cryotherapy, surgical excision, shave excision, curettage and laser are based on physical destruction of the visible lesions. Field-targeted treatments are effective in the treatment of visible lesions, subclinical lesions and keratinocyte changes in the areas surrounding the visible lesions. Field targeted treatment options are topical imiquimod cream, 5% 5-fluorouracil cream, ingenol mebutate, diclofenac gel, resimiquimod and photodynamic therapy.

Field cancerization in the colon:a role for aberrant DNA methylation?

Colorectal cancer is the third most common cancer worldwide and arises secondary to the progressive accumulation of genetic and epigenetic alterations in normal colon cells,which results in a polyp-to-cancer progression sequence.It is known that individuals with a personal history of colon adenomas or cancer are at increased risk for metachronous colon neoplasms.One explanation for this increased risk could be field cancerization,which is a phenomenon in which the histologically normal tissue in an organ is primed to undergo transformation.Epigenetic alterations appear to be promising markers for field cancerization.In this review,we discuss field cancerization in the colon and the data supporting the use of methylated DNA as a biomarker for this phenomenon.

Cancer field： A new concept

The proceeding of cancer development seems to be driven by the complex interaction among cells, stroma and adjacent tissue. Here we advocate a new conception, cancer field, to describe the development of cancer, a complex adaptive system. Cancer field may be divided into center of tumor, periphery of tumor and adjacent tissue. The balance of inhibitors and inducers, including the interaction among cancer cells, niche and adjacent tissue, governs the switch of development of cancer field, which mimic embryonic development, a dynamic process of self-organization. The radial component of intra-tumor heterogeneity raises the field change effects in cancer field. Research strategy may be changed from single cancer cell to cancer field, from malignant transform to cancer development biology.

Cancer field surgery for locoregional tumor control of cervical carcinoma

As the current standard,surgery is applied to treat early-stage cervical cancer and selected post-irradiation pelvic relapses.Surgical therapy for local disease is based on a model of unlimited isotropic cancer cell propagation and dissection artifacts such as subperitoneal“ligaments”and“spaces”.For regional disease,the role of traditional surgery is diagnostic and eventually cytoreductive.However,the isotropic local tumor propagation model has to be rejected due to numerous inconsistencies with clinical facts.Likewise,the“ligament and space”approach to the subperitoneum is too crude and variable to accurately cover both local spread and intercalated lymph node metastases of cervical cancer.The ontogenetic cancer field model is fully in line with the locoregional spread patterns of carcinoma of the female genital tract.Developmentally derived(ontogenetic)anatomy enables unbiased and accurate dissection of the complex tissue structures within the subperitoneum.Cancer field surgery founded on these insights has a high potential to improve the treatment outcome of cervical carcinoma.