Radiotherapy for rectal cancer is associated with reduced serum testosterone and increased FSH and LH.
OBJECTIVE
It is known that scattered radiation to the testes during pelvic radiotherapy can affect fertility, but there is little knowledge on its effects on male sex hormones. The aim of this study was to determine whether radiotherapy for rectal cancer affects testosterone production.


METHODS
All male patients who had received adjuvant radiotherapy for rectal cancer from 1993 to 2003 were identified from the Norwegian Rectal Cancer Registry. Patients treated with surgery alone were randomly selected from the same registry as control subjects. Serum levels of follicle stimulating hormone (FSH), luteinizing hormone (LH), testosterone, and sex hormone binding globulin (SHBG) were analyzed, and free testosterone was calculated (N = 290). Information about the radiotherapy treatment was collected from the patient hospital charts.


RESULTS
Serum FSH was 3 times higher in the radiotherapy group than in the control group (median, 18.8 vs. 6.3 IU/L, p <0.001), and serum LH was 1.7 times higher (median, 7.5 vs. 4.5 IU/l, p <0.001). In the radiotherapy group, 27% of patients had testosterone levels below the reference range (8-35 nmol/L), compared with 10% of the nonirradiated patients (p <0.001). Irradiated patients had lower serum testosterone (mean, 11.1 vs. 13.4 nmol/L, p <0.001) and lower calculated free testosterone (mean, 214 vs. 235 pmol/L, p <0.05) than control subjects. Total testosterone, calculated free testosterone, and gonadotropins were related to the distance from the bony pelvic structures to the caudal field edge.


CONCLUSIONS
Increased serum levels of gonadotropins and subnormal serum levels of testosterone indicate that curative radiotherapy for rectal cancer can result in permanent testicular dysfunction.
Bruheim
Kjersti
K
The Cancer Center, Ullevaal University Hospital, Oslo, Norway. Kjersti.Bruheim@medisin.uio.no
Svartberg
Johan
J
Carlsen
Erik
E
Dueland
Svein
S
Haug
Egil
E
Skovlund
Eva
E
Tveit
Kjell Magne
KM
Guren
Marianne G
MG
D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D005640:Follicle Stimulating Hormone / Q000097:blood*; D006801:Humans; D007986:Luteinizing Hormone / Q000097:blood*; D008297:Male; D018714:Radiotherapy, Adjuvant; D012004:Rectal Neoplasms / Q000097:blood* / Q000532:radiotherapy* / Q000601:surgery; D012542:Scattering, Radiation; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism; D013737:Testis / Q000378:metabolism / Q000528:radiation effects*; D013739:Testosterone / Q000097:blood*
D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone