title: Secondary Cancers After Radiation Therapy for Primary Prostate or Rectal Cancer.
abstract: Literature about the risk of secondary cancer after radiation therapy (RT) of prostate and rectal cancer reveals contradictory results. We conducted a meta-analysis to examine whether the RT induces secondary rectal or prostate cancer in patients, respectively, with prostate or rectal cancer. All studies published in Medline or Pubmed up to March 3, 2015, containing RT of primary rectal or prostate cancer, and providing risk estimates of secondary prostate or rectal cancer were considered as eligible. Relative risk (RR) and standardized incidence ratios (SIR) were calculated using the random-effects model. Twenty studies met the inclusion criteria. 12 of them were from the Surveillance, Epidemiology, and End Results (SEER) database. For prostate cancer patients, pooled adjusted RRs or SIRs did not show an effect on the risk of secondary rectal cancer. However, notwithstanding the limitations of SEER-based studies, the subgroup of prostate cancer patients receiving external beam radiation therapy (EBRT) showed an increased risk of rectal cancer. For rectal cancer patients, pooled adjusted RR of prostate cancer was 1.12 (95 % CI, 0.44-2.8) and SIR was 0.40 (95 % CI, 0.29-0.55). All studies included in the SIR analysis of rectal cancer were derived from the SEER data source. Based on current evidence, RT for prostate cancer patients had no effect on rectal cancer incidence, except for patients who received EBRT therapy. However, compared with the general population, RT for rectal cancer is associated with a decreased prostate cancer risk as found in SEER-based studies.
authors.affiliation: Institute of Clinical Medicine, National Cheng Kung University College of Medicine, Tainan, Taiwan, ROC. yc_lee@post.harvard.edu.|Department of Oncology, Tainan Hospital, Ministry of Health and Welfare, No. 125, Jhongshan Rd, Tainan, 70043, Taiwan, ROC. yc_lee@post.harvard.edu.
authors.forename: Yen-Chien
authors.initials: YC
authors.lastname: Lee
authors.affiliation: Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, US 364 Plantation Street, LRB#427, Worcester, MA, 01605, USA. chung-cheng.hsieh@umassmed.edu.
authors.forename: Chung-Cheng
authors.initials: CC
authors.lastname: Hsieh
authors.affiliation: Department and Graduate Institute of Public Health, College of Medicine, National Cheng Kung University, University Road, Tainan, 701, Taiwan, ROC. cyli99@mail.ncku.edu.tw.
authors.forename: Chung-Yi
authors.initials: CY
authors.lastname: Li
authors.affiliation: Institute of Clinical Medicine, National Cheng Kung University College of Medicine, Tainan, Taiwan, ROC. chuangjp@gmail.com.|Department of Surgery, Tainan Hospital, Ministry of Health and Welfare, Tainan, Taiwan, ROC. chuangjp@gmail.com.
authors.forename: Jen-Pin
authors.initials: JP
authors.lastname: Chuang
authors.affiliation: Departments of Surgery, National Cheng Kung University Medical Center, No. 138, Sheng Li Road, Tainan, 704, Taiwan, ROC. leejc@mail.ncku.edu.tw.
authors.forename: Jenq-Chang
authors.initials: JC
authors.lastname: Lee
mesh_terms: D001918:Brachytherapy / Q000706:statistics & numerical data*; D006801:Humans; D015994:Incidence; D008297:Male; D016609:Neoplasms, Second Primary / Q000453:epidemiology*; D016016:Proportional Hazards Models; D011471:Prostatic Neoplasms / Q000453:epidemiology / Q000532:radiotherapy*; D011878:Radiotherapy / Q000706:statistics & numerical data; D012004:Rectal Neoplasms / Q000453:epidemiology / Q000532:radiotherapy*; D012307:Risk Factors