Postoperative radiation therapy for surgically staged endometrial cancer: impact of time factors (overall treatment time and surgery-to-radiation interval) on outcome.
OBJECTIVE
To evaluate the impact of prolonged overall radiation treatment (RT) time and surgery-to-radiation interval on local control (LC) and disease-specific survival (DSS) of surgically staged endometrial cancer patients in relation to known prognostic factors.


METHODS
Between 1971 and 1993, 195 endometrial cancer patients received postoperative RT at the Fox Chase Cancer Center. All patients underwent total abdominal hysterectomy (TAH), with 38% also having lymph node sampling. All patients received whole pelvic external beam RT to a median dose of 45 Gy (range 40 to 60 Gy). Sixty-nine percent received a vaginal cuff boost with either low dose rate or high dose rate brachytherapy. Tumor and treatment factors were analyzed for impact on LC and DSS. Median follow-up was 47 months (range: 6 to 187 months).


RESULTS
The overall actuarial 5-year LC rate was 85%. In multivariate analysis, tumor grade, pathologic stage, external radiation dose, and surgical lymph node evaluation were independent prognostic variables for improved LC. Surgery-to-radiation interval of greater than 6 weeks was a marginally significant factor for decreased LC (p = 0.06). Overall RT time and external beam treatment time did not appear to impact LC rates. The overall actuarial 5-year DSS rate was 86%. In multivariate analysis, depth of myometrial invasion, tumor grade, and pathologic stage were independent prognostic variables for DSS. In addition, a surgery-to-radiation interval of greater than 6 weeks was significantly associated with decreased DSS (p < 0.005).


CONCLUSIONS
Surgery-to-radiation interval of greater than 6 weeks is a significant independent prognostic variable for decreased DSS and a marginally significant variable for decreased LC in patients irradiated postoperatively for endometrial cancer. Other time factors (overall RT time and external beam treatment time) did not appear to impact outcome. Based on this analysis, postoperative radiation therapy for endometrial cancer should be initiated within 6 weeks following surgery.
Ahmad
N R
NR
Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA, USA.
Lanciano
R M
RM
Corn
B W
BW
Schultheiss
T
T
D000206:Actuarial Analysis; D000704:Analysis of Variance; D015331:Cohort Studies; D003131:Combined Modality Therapy; D018572:Disease-Free Survival; D016889:Endometrial Neoplasms / Q000401:mortality* / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D005260:Female; D006801:Humans; D008875:Middle Aged; D011184:Postoperative Period; D013997:Time Factors; D016896:Treatment Outcome