Identification of a rectal subregion highly predictive of rectal bleeding in prostate cancer IMRT.

BACKGROUND AND PURPOSE: To identify rectal subregions at risks (SRR) highly predictive of 3-year rectal bleeding (RB) in prostate cancer IMRT. MATERIALS AND METHODS: Overall, 173 prostate cancer patients treated with IMRT/IGRT were prospectively analyzed, divided into "training" (n=118) and "validation" cohorts (n=53). Dose-volume histograms (DVHs) were calculated in three types of rectal subregions: "geometric", intuitively defined (hemi-rectum,…); "personalized", obtained by non-rigid registration followed by voxel-wise statistical analysis (SRRp); "generic", mapped from SRRps, located within 8×8 rectal subsections (SRRg). DVHs from patients with and without RB were compared and used for toxicity prediction. RESULTS: Training cohort SRRps were primarily within the inferior anterior hemi-rectum and upper anal canal, with 3.8Gy mean dose increase for Grade⩾1 RB patients. The SRRg, representing 15% of the absolute rectal volume, was located in 10 inferior-anterior rectal subsections. V18-V70 for SRRps and V58-V65 for SRRg were significantly higher for RB patients than non-RB. Maximum areas under the curve (AUCs) for SRRp and SRRg RB prediction were 71% and 64%, respectively. The validation cohort confirmed the predictive value of SRRg for Grade⩾1 RB. The total cohort confirmed the predictive value of SRRg for Grade⩾2 RB. Geometrical subregions were not RB predictors. CONCLUSION: The inferior-anterior hemi anorectum was highly predictive of RB.

The essential role of radiotherapy in the treatment of Merkel cell carcinoma: a study from the Rare Cancer Network.

PURPOSE: To evaluate the role of postoperative radiotherapy (RT) in Merkel cell carcinoma (MCC). METHODS AND MATERIALS: A retrospective multicenter study was performed in 180 patients with MCC treated between February 1988 and September 2009. Patients who had had surgery alone were compared with patients who received surgery and postoperative RT or radical RT. Local relapse-free survival (LRFS), regional relapse-free survival (RRFS), and distant metastasis-free survival (DMFS) rates were assessed together with disease-free survival (DFS), cancer-specific survival (CSS), and overall survival (OS) rates. RESULTS: Seventy-nine patients were male and 101 patients were female, and the median age was 73 years old (range, 38-93 years). The majority of patients had localized disease (n = 146), and the remaining patients had regional lymph node metastasis (n = 34). Forty-nine patients underwent surgery for the primary tumor without postoperative RT to the primary site; the other 131 patients received surgery for the primary tumor, followed by postoperative RT (n = 118) or a biopsy of the primary tumor followed by radical RT (n = 13). Median follow-up was 5 years (range, 0.2-16.5 years). Patients in the RT group had improved LRFS (93% vs. 64%; p < 0.001), RRFS (76% vs. 27%; p < 0.001), DMFS (70% vs. 42%; p = 0.01), DFS (59% vs. 4%; p < 0.001), and CSS (65% vs. 49%; p = 0.03) rates compared to patients who underwent surgery for the primary tumor alone; LRFS, RRFS, DMFS, and DFS rates remained significant with multivariable Cox regression analysis. However OS was not significantly improved by postoperative RT (56% vs. 46%; p = 0.2). CONCLUSIONS: After multivariable analysis, postoperative RT was associated with improved outcome and seems to be an important component in the multimodality treatment of MCC.

The GETUG 70 Gy vs. 80 Gy randomized trial for localized prostate cancer: feasibility and acute toxicity.

PURPOSE: To describe treatments and acute tolerance in a randomized trial comparing 70 Gy and 80 Gy to the prostate in patients with localized prostate cancer. METHODS AND MATERIALS: Between September 1999 and February 2002, 306 patients were randomized to receive 70 Gy (153 patients) or 80 Gy (153 patients) in 17 institutions. Patients exhibited intermediate-prognosis tumors. If the risk of node involvement was greater than 10%, surgical staging was required. Previous prostatectomy was excluded, and androgen deprivation was not admitted. The treatment was delivered in two steps. PTV1-including seminal vesicles, prostate, and a 1-0.5-cm margin-received 46 Gy given with a 4-field conformal technique. PTV2, reduced to prostate with the same margins, irradiated with at least 5 fields. Dose was prescribed according to ICRU recommendations in the 70 Gy group, but adapted at the 80 Gy level. RESULTS: All patients but one in the 80 Gy arm completed the treatment. In the 70 Gy arm, the mean dose to the PTV2 was 69.5 Gy. In the 80 Gy arm, the mean dose in the PTV2 was 78.5 Gy. Acute toxicity according to Radiation Therapy Oncology Group scale during treatment was reported in 306 patients. There was no statistically significant difference between the two arms: 12% had no toxicity, 80% complained of bladder toxicity, and 70% complained of rectal symptoms. Two months after the end of treatment, 43% of the 70 Gy level and 48% of the 80 Gy level complained of side effects, including 24% and 20% of sexual disorders. There was 6% and 2% of Grade 3 urinary and rectal toxicity. Five patients required a 10-29-day suspension of the treatment. Acute Grade 2 and 3 side effects were related to PTV and CTV1 size, which was the only independent predictive factor in multivariate analysis. Toxicity was not related to the center, age, arm of treatment, or selected data from dose-volume histogram of organ at risk. CONCLUSION: Treatments were completed in respect to constraints. Acute toxicity was acceptable. Intensity of toxicity depended on target volumes.