Correlation between dose-volume parameters and rectal bleeding after 12 fractions of carbon ion radiotherapy for prostate cancer

BACKGROUND Carbon ion radiotherapy(CIRT)is currently used to treat prostate cancer.Rectal bleeding is a major cause of toxicity even with CIRT.However,to date,a correlation between the dose and volume parameters of the 12 fractions of CIRT for prostate cancer and rectal bleeding has not been shown.Similarly,the clinical risk factors for rectal bleeding were absent after 12 fractions of CIRT.AIM To identify the risk factors for rectal bleeding in 12 fractions of CIRT for prostate cancer.METHODS Among 259 patients who received 51.6 Gy[relative biological effectiveness(RBE)],in 12 fractions of CIRT,15 had grade 1(5.8%)and nine had grade 2 rectal bleeding(3.5%).The dose-volume parameters included the volume(cc)of the rectum irradiated with at least x Gy(RBE)(Vx)and the minimum dose in the most irradiated x cc normal rectal volume(Dx).RESULTS The mean values of D6cc,D2cc,V10 Gy(RBE),V20 Gy(RBE),V30 Gy(RBE),and V40 Gy(RBE)were significantly higher in the patients with rectal bleeding than in those without.The cutoff values were D6cc=34.34 Gy(RBE),D2cc=46.46 Gy(RBE),V10 Gy(RBE)=9.85 cc,V20 Gy(RBE)=7.00 cc,V30 Gy(RBE)=6.91 cc,and V40 Gy(RBE)=4.26 cc.The D2cc,V10 Gy(RBE),and V20 Gy(RBE)cutoff values were significant predictors of grade 2 rectal bleeding.CONCLUSION The above dose-volume parameters may serve as guidelines for preventing rectal bleeding after 12 fractions of CIRT for prostate cancer.

Modified simultaneous integrated boost radiotherapy for an unresectable huge refractory pelvic tumor diagnosed as a rectal adenocarcinoma

A clinical trial of radiotherapy with modified simultaneous integrated boost(SIB)technique against huge tumors was conducted.A 58-year-old male patient who had a huge pelvic tumor diagnosed as a rectal adenocarcinoma due to familial adenomatous polyposis was enrolled in this trial.The total dose of 77 Gy(equivalent dose in 2Gy/fraction)and 64.5 Gy was delivered to the center of the tumor and the surrounding area respectively,andapproximately 20%dose escalation was achieved with the modified SIB technique.The tumor with an initial maximum size of 15 cm disappeared 120 d after the start of the radiotherapy.Performance status of the patient improved from 4 to 0.Radiotherapy with modified SIB may be effective for patients with a huge tumor in terms of tumor shrinkage/disappearance,improvement of QOL,and prolongation of survival.

Bladder-Sparing Approach with Radiotherapy in Patients with Small Cell Carcinoma of the Bladder

Small cell carcinoma (SCCB) of the bladder is rare and has a poor prognosis. Because of its rarity, gold standard care has not been established. The purpose of this study was to analyze the feasibility of a bladder-sparing approach. Data for treatments and outcomes in patients with a diagnosis of SCCB who received bladder-sparing treatment in our facility in the period from February 2007 to August 2012 were retrospectively analyzed. Six eligible patients received definitive radiotherapy in the cancer network of Tohoku region. Mean age of the patients was 69.5 years (range: 44 - 83 years), and median follow-up period was 29.2 months (range: 4.1 - 54.5 months). The mean dose was 60 Gy (range: 60 to 63 Gy), and 1.2 - 2.0 Gy was given per fraction. The initial CTV was the whole pelvis or the small pelvis, and it was shrunk to the bladder or tumor as a boost. The 1-year and 3-year overall survival rates were 83.3% and 55.6%, respectively. The 1-year and 3-year local control rates were both 80.0%. Only one patient had local failure. Recurrence or metastasis in sites other than the brain occurred in three (50%) of the patients after primary treatment. Two of those patients did not receive any chemotherapy. None of the patients had serious toxicities, and the bladder could be preserved in all patients. In this study, radiotherapy was effective for patients with SCCB. There was no recurrence in the bladder, and it was possible to preserve the bladder in all patients. Distant metastases were observed frequently, and chemotherapy was considered to be essential. Local treatment with radiotherapy has an important role from the point of view of the patient’s QOL.