title: Testicular function after radiotherapy for rectal cancer--a review.
abstract: BACKGROUND
  Eighty percent of all male rectal cancer patients are sexually active at the time of diagnosis. Because of modern multimodal therapy many can expect long-term survival. The testes can be exposed to scattered or direct radiation during radiotherapy, depending on their position in relation to the targeted volume.
  
  
  OBJECTIVE
  This review analyzes the current literature providing data on testicular exposure to radiation during radiotherapy for rectal cancer and the consequences on testicular function.
  
  
  METHODS
  A systematic search was conducted in PubMed, Embase, and Cochrane. Ten original articles providing data on testicular exposure to radiation and testicular function in men with primary rectal cancer were included for qualitative synthesis.
  
  
  METHODS
  Data on testicular exposure to radiation and testosterone levels in men with rectal cancer are reported.
  
  
  RESULTS
  On average, the testes were exposed to 0.24-8.4 Gy during long-course radiotherapy for rectal cancer. Testosterone levels after radiation were significantly lower compared with pretreatment levels or compared with patients treated with surgery alone. After radiotherapy, the absolute risk increase was 0.17-0.30 for posttreatment testosterone levels below 8 nmol/L. In the largest study, the relative risk was 2.7 for testosterone levels below 8 nmol/L for men treated with radiotherapy compared with men treated with surgery alone.
  
  
  CONCLUSIONS
  Current data generate three hypotheses: (i) during long-course radiotherapy for rectal cancer, the testes can be exposed to direct and/or scattered radiation; (ii) men treated with radiotherapy seem at risk to develop testicular dysfunction with decreased serum testosterone levels compared with both pretreatment values and men treated with surgery alone; and (iii) a decrease in testosterone levels (<8 nmol/L) may precipitate specific symptoms caused by testosterone deficiency such as impaired physical, psychological, and sexual function after treatment.
authors.affiliation: Department of Molecular Medicine and Surgery, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden. christian.buchli@karolinska.se
authors.forename: Christian
authors.initials: C
authors.lastname: Buchli
authors.forename: Anna
authors.initials: A
authors.lastname: Martling
authors.forename: Stefan
authors.initials: S
authors.lastname: Arver
authors.forename: Torbjörn
authors.initials: T
authors.lastname: Holm
mesh_terms: D007172:Erectile Dysfunction / Q000209:etiology; D006801:Humans; D008297:Male; D011829:Radiation Dosage; D012004:Rectal Neoplasms / Q000532:radiotherapy*; D013091:Spermatogenesis / Q000528:radiation effects; D013737:Testis / Q000502:physiology / Q000528:radiation effects*; D013739:Testosterone / Q000097:blood
chemical_list: D013739:Testosterone