Radiation therapy for prostate cancer increases the risk of subsequent rectal cancer.

PURPOSE: To assess whether radiation therapy for prostate cancer (PCa) increases the risk of metachronous rectal cancer (RCa) and compare outcomes of RCa after radiation therapy and surgery. PATIENTS AND METHODS: The Israel Cancer Registry was queried to identify patients with PCa and RCa diagnosed between 1982 and 2005. The age adjusted standardized incidence ratio (SIR) of RCa was defined as the ratio between the observed and expected (calculated) RCa cases and compared among the following: overall Israeli male population, patients with PCa treated with radiation therapy, patients with PCa treated surgically. The medical records of men diagnosed with RCa were reviewed and clinical characteristics retrieved. RESULTS: Of 29,593 men diagnosed with PCa, 2163 were treated with radiation therapy, 6762 were treated surgically and 20,068 patients were treated with either primary androgen deprivation therapy or offered watchful waiting. Of the entire study cohort, 194 (0.65%) patients were diagnosed with subsequent RCa. Compared to the overall male population and stratified by treatment modality, the risk of developing RCa after radiation therapy was significantly increased (SIR = 1.81, 95% CI 1.2-2.5), whereas it was not increased in those managed by surgery (SIR = 1.22, 95% CI 0.85-1.65). RCa after radiation therapy was diagnosed at a more advanced stage, translating into inferior disease specific survival. CONCLUSIONS: Compared to men diagnosed with PCa managed by surgery, we observed an increased risk of RCa in patients treated with radiation therapy. Further studies are needed to validate these findings and assess whether routine colonoscopic surveillance is warranted after pelvic radiation.

A higher detection rate for colorectal cancer and advanced adenomatous polyp for screening with immunochemical fecal occult blood test than guaiac fecal occult blood test, despite lower compliance rate. A prospective, controlled, feasibility study.

Immunochemical fecal occult blood test (FIT) is a new colorectal cancer (CRC) screening method already recommended by the American screening guidelines. We aimed to test the feasibility of FIT as compared to guaiac fecal occult blood test (G-FOBT) in a large urban population of Tel Aviv. Average-risk persons, aged 50-75 years, were offered FIT or G-FOBT after randomization according to the socioeconomic status of their clinics. Participants with positive tests underwent colonoscopy. Participants were followed through the Cancer Registry 2 years after the study. Hemoccult SENSA™ and OC-MICRO™ (three samples, 70 ng/ml threshold) were used. FIT was offered to 4,657 persons (Group A) and G-FOBT to 7,880 persons (Group B). Participation rate was 25.9% and 28.8% in Group A and B, respectively (p < 0.001). Positivity rate in Group A and B was 12.7% and 3.9%, respectively (p < 0.001). Cancer found in six (0.49%) and eight (0.35%) patients of Group A and B, respectively (NS). Cancer registry follow-up found missed cancer in five (0.22%) cases of Group B and none in Group A (NS). The sensitivity, specificity, negative and positive predictive value for cancer in Group A and B were 100%, 85.9%, 100%, 3.9% and 61.5%, 96.4%, 99.8%, 9.1%, respectively. There was increased detection of advanced adenomatous polyp (AAP) by FIT, irrespective of age, gender, and socioeconomic status (Per Protocol: odds ratio 2.69, 95% confidence interval 1.6-4.5; Intention to Screen: odds ratio 3.16, 95% confidence interval 1.8-5.4). FIT is feasible in urban, average-risk population, which significantly improved performance for detection of AAP and CRC, despite reduced participation.