Rectal cancer epidemiology prognosis associated with pre-operative chemoradiation therapy and secondary prostate cancer from post radiation therapy

Abstract

Purposes: Colorectal cancer is the third most commonly diagnosed cancer in male and female worldwide Rectal cancer accounts for 30 to 35% of colorectal cancer cases Chemoradiation therapy has been the standard treatment nowadays for rectal cancer at stage T3/N(+) This study aimed to (1) describe rectal cancer epidemiology; (2) investigate whether prognosis was associated with tumor regression grading in rectal cancer patients with pre-operative chemoradiation therapy? and (3) assesse risk of secondary cancer onset from post radiation therapy Materials and Methods: Data analyzed included colorectal cancer (1995–2008) from the Surveillance Epidemiology and End Results Program (SEER) database Only adenocarcinoma was included for the analysis Systematic review and meta-analysis were conducted to investigate the prognosis associated with partial and poor tumor regression in rectum cancer patients with chemoradiation therapy We also performed another systematic review and meta-analysis to summarize the evidence concerning the risk of prostate cancer following chemoradiation therapy Finally we used the National Health Insurance Research Database (NHIRD) to identify male rectal cancer patients who underwent surgery With a cohort study design this study compared the subsequent risks of prostate cancer between the patients receiving radiation therapy within one year after diagnosis of rectal cancer and those receiving no radiation therapy Results: Around 35% of patients had cancer stage information Among them colon cancer patients had better survival than those with rectal cancer by a margin of 4 months in stage IIB In stage IIIC and stage IV rectal cancer patients had better survival than colon cancer patients by about 3 months Stage IIB colorectal cancer patients had a poorer prognosis than those with stage IIIA and IIIB colorectal cancer After adjustment of age sex and race colon cancer patients had better survival than rectal cancer of stage IIB but in stage IIIC and IV rectal cancer patients had better survival than colon cancer As for chemoradiation effects of rectal cancer pooled hazard ratio (HR) was 0 49 (95% Confidence Interval (CI) 0 28–0 85) for the 6 studies that excluded all patients with complete response and compared partial response with poor response It was 0 41 (95% CI 0 25–0 67) when all 11 of the studies were analyzed together Regarding late effects of chemoradiation therapy of rectal cancer the summary data of 5 studies reported no significant increase in risk of prostate cancer pooled HR=1 12 (95% CI 0 44-2 80) in rectum cancer patients receiving chemoradiation therapy as opposed to those who do not have such therapy On the other hand chemoradiation therapy was associated with a significantly reduced standardized incidence ratio (SIR) (0 40 95% CI 0 29-0 55) of prostate cancer in rectum cancer patients as compared to the general population Male rectal cancer patients from NHIRD showed increased prostate cancer incidence after receiving radiation therapy within 1 year diagnosis of rectal cancer compared with those without receiving any radiation therapy (HR 1 73; 95% CI 1 59-1 88) Conclusion: Prognosis of rectal cancer was not worse than that of colon cancer Local advanced colorectal cancer had a poorer prognosis than local regional lymph node metastasis Stage IIB might require more aggressive chemotherapy and no less than that for stage III Partial tumor response of chemoradiation therapy of rectal cancer is associated with a 50% improvement in disease-free survival and should be considered as a favorable prognostic factor According to the current evidence rectum cancer patients who received radiation therapy showed no significant effect on prostate cancer incidence as compared to rectal cancer patients who received no such therapy but showed a significantly reduced risk of prostate cancer as compared to the general population The present cohort analysis demonstrated that radiation therapy for rectal cancer is associated with a increased prostate cancer risk of prostate cancer

Date of Award	2016 Jan 26
Original language	English
Supervisor	Chung-Yi Li (Supervisor)