title: Secondary malignancies after rectal cancer resection with and without radiation therapy: A propensity-adjusted, population-based SEER analysis.
abstract: The relationship between radiation therapy for rectal cancer and secondary malignancies is debated. The present study is the first population-based analysis using conventional multivariable analyses as well as propensity score matching to assess this relationship.
  
  
  
  Overall, 77,484 patients after resection of localized or locally advanced rectal adenocarcinoma diagnosed between 1973 and 2012 were identified in the Surveillance, Epidemiology, and End Results (SEER) registry. The occurrence of secondary malignancies diagnosed at least 1 (median follow up 5.8years [1-39.9years]) year after rectal cancer diagnosis was compared in patients who did and did not undergo radiation using stratified and propensity score matched Cox regression analysis.
  
  
  
  Of 77,484 patients, 34,114 underwent radiation and 43,370 did not. Ignoring gender and entity, radiation therapy was not associated with secondary malignancies (hazard ratio [HR]=0.97 (95%CI: 0.92-1.02, P=0.269). The risk for prostate cancer was decreased and (HR=0.42, 95%CI: 0.36-0.48, P<0.001) and increased risk for endometrial cancer (HR=1.95, 95%CI: 1.49-2.56, P<0.001). Overall, patients undergoing radiation had higher risks for lung cancer (HR=1.18, 95%CI: 1.06-1.30, P<0.001), bladder cancer (HR=1.54, 95%CI: 1.31-1.80, P<0.001) and lymphomas (HR=1.27, 95%CI: 1.03-1.58, P=0.026).
  
  
  
  The present analysis describes the occurence of secondary malignancies after pelvic radiation in patients undergoing rectal cancer surgery. Indeed, radiation for rectal cancer is associated with a significantly decreased risk of prostate cancer, however, an increased risk of endometrial, lung, and bladder cancer as well as lymphomas was observed. Overall, the risk of secondary malignancies was slightly decreased with radiation in patients undergoing rectal cancer resection, this was attributable to lower rates in prostate cancer.
authors.affiliation: Department of Surgery, Cantonal Hospital, St.Gallen, Switzerland; Institute of Medical Biometry and Informatics, University of Heidelberg, Germany.
authors.forename: Rene
authors.initials: R
authors.lastname: Warschkow
authors.affiliation: Department of Medical Oncology and Hematology, Cantonal Hospital, St.Gallen, Switzerland; Department of Visceral Surgery and Medicine, University of Berne, Switzerland.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Güller
authors.affiliation: Department of Visceral Surgery and Medicine, University of Berne, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Cerny
authors.affiliation: Department of Surgery, Cantonal Hospital, St.Gallen, Switzerland.
authors.forename: Bruno Martin
authors.initials: BM
authors.lastname: Schmied
authors.affiliation: Department of Radiation Oncology, Cantonal Hospital, St.Gallen, Switzerland.
authors.forename: Ludwig
authors.initials: L
authors.lastname: Plasswilm
authors.affiliation: Department of Radiation Oncology, Cantonal Hospital, St.Gallen, Switzerland. Electronic address: Paul.Putora@kssg.ch.
authors.forename: Paul Martin
authors.initials: PM
authors.lastname: Putora
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000209:etiology*; D057216:Propensity Score; D016016:Proportional Hazards Models; D011471:Prostatic Neoplasms / Q000209:etiology; D012004:Rectal Neoplasms / Q000532:radiotherapy / Q000601:surgery*; D018426:SEER Program; D001749:Urinary Bladder Neoplasms / Q000209:etiology
keywords: Epidemiology and End Results (SEER) database; Propensity score; Radiation; Rectal cancer; Surveillance