Systematic irradiation of the vaginal vault in stage I endometrial carcinoma

The influence of applicator angle on dosimetry in vaginal vault brachytherapy

In vaginal vault brachytherapy, the critical normal tissues are bladder and rectum; doses to these tissues may be affected by the position of a single line applicator placed in the vagina. Dosimetry with the applicator lying at its "natural" angle in the vagina with the patient in the lithotomy position has been compared with the applicator held horizontal as defined by a spirit level in 30 consecutive patients. A mean change in angle of 19.7 degrees was found. This resulted in a mean decrease in ICRU (International Commission of Radiation Units and Measurements) rectal point dose when the applicator is horizontal of 12.9%, equivalent to a mean absolute dose reduction of 1.3 Gy for a prescription dose of 5.5 Gy at 5 mm depth. An increase in mean dose to the ICRU bladder point when the applicator is horizontal of 13.3%, equivalent to an absolute mean dose increase of 0.5 Gy per fraction for the same prescription dose, was also found. On the basis of these findings, it is recommended that vaginal vault brachytherapy is performed with a single line source held in the "corrected" horizontal position to reduce bowel dose as this is the most sensitive critical normal tissue.

Vaginal vault brachytherapy: the effect of varying bladder volumes on normal tissue dosimetry

This study was designed to assess the impact of bladder volume on dosimetry to critical normal structures in vaginal vault brachytherapy using a single line source vaginal applicator. 30 consecutive patients undergoing vaginal vault brachytherapy were studied by CT scanning with the applicator in situ and the bladder empty and then with the bladder containing either 35 ml of water (10 patients), 70 ml of water (10 patients) or 100 ml of water (10 patients). The scans were then analysed with isodose distributions overlayed to determine changes in dosimetry. No effect on bladder dose was seen with increasing volume compared with the empty bladder; however, there was a reduction in amount of small bowel within the high dose treatment region as bladder volume increased. With 100 ml bladder volume, the reduction reached 57.5% compared with the empty bladder. We conclude that vaginal vault brachytherapy should be undertaken with a bladder volume of at least 100 ml, which will considerably reduce the amount of small bowel in the irradiation volume with no increase in bladder dose.

The role of adjuvant radiotherapy in carcinoma of the endometrium-results in 550 patients with pathologic stage I disease

OBJECTIVES

A retrospective analysis of 550 women with pathological stage I carcinoma of the endometrium who were seen between January 1984 and December 1988 was performed in order to assess the value of adjuvant radiation therapy.

METHODS

Two-hundred twenty-eight patients were treated with surgery alone (S); 97 received adjuvant external beam radiotherapy (S + EXT); 217 received external beam radiotherapy and colpostats (S + EXT + IC); and 8 patients received only colpostats (S + IC). Pelvic radiation therapy, usually 40 Gy in 20 fractions, was administered to 94% of patients whose tumors showed greater than 50% myometrial invasion and to 89% of patients with FIGO grade 3 tumors. Colpostats were used in 40% of patients, the majority of whom had lower uterine segment involvement.

RESULTS

The overall survival rate for the whole group using Kaplan-Meier estimates was 84% at 5 years. The 5-year overall survival rates for each treatment group, excluding the S + IC group, were 90% for S alone, 79% for S + EXT, and 82% for S + EXT + IC. The 5-year disease-free survival rates were 84, 77, and 77%, respectively. Local control rates at 5 years were 93, 94, and 95% in the three treatment groups, but the patterns of relapse were different. Distant metastases occurred more frequently among the patients who received adjuvant radiation therapy (36/49, 73%) than among those who did not (4/19, 21%). Late toxicity was documented in 66 patients. Twelve patients had EORTC/RTOG grade 3 and 4 complications; all had been treated with S + EXT + IC. FIGO grade (P = 0.009), lower uterine segment involvement (P = 0.009), and age (P = 0.03) were significant predictors of worse disease-free survival in a multiple regression analysis.

CONCLUSIONS

The addition of vaginal vault brachytherapy to external beam radiotherapy did not appear to improve local cure rates nor survival, but increased the incidence of late radiation toxicity.

Uterine cancer (corpus uteri)

This synthesis of the literature on radiotherapy for cancer originating in the endometrium of the uterus (corpus uteri) is based on 55 scientific articles, including 2 randomized studies, 1 prospective study, and 48 retrospective studies. These studies involve 13597 patients. Endometrial cancer is a radiosensitive cancer. Research findings compiled for the period 1948 to 1954 showed that 69% of the patients could be cured by radiotherapy alone. During the 1970s it was shown that combined radiotherapy and surgery yielded better results. There is agreement that patients at stage I should receive primary surgery. According to the literature, there is controversy about whether patients with poorly differentiated tumors should be given preoperative radiotherapy. Radiotherapy alone can be used successfully in patients who are inoperable because of age, general condition, or advanced spread of cancer. Vaginal postoperative radiotherapy is used in most patients and reduces the percentage of patients who develop vaginal metastases from 7%-20% to less than 1%. Patients with good prognostic factors have such a low risk for metastasis that withholding radiotherapy may be considered in this group. Postoperative external radiotherapy improves survival in patients with unfavorable prognostic factors, such as deep myometrium invasion or signs of node metastasis. Radiotherapy is delivered, in principle, to all patients with poorly differentiated disease. It can be expected that most cases of endometrial cancer will continue to be referred for some form of radiotherapy.

Role of intracavitary cuff boost after adjuvant external irradiation in early endometrial carcinoma

Management of early endometrial carcinoma often consists of surgicopathologic staging followed by adjuvant radiation therapy (RT) for patients at risk of local recurrence. While an intracavitary vaginal cuff boost (VCB) is commonly given after external beam radiation therapy, its effects on local control and complication rates are unknown. To assess these effects, we reviewed 157 patients with FIGO Stage I (n = 134) or incidentally diagnosed (n = 23) endometrial adenocarcinomas. After surgery and external radiation therapy, 103 patients (65.6%) received a vaginal cuff boost of 3000-5000 cGy surface dose (Group I) and 54 (34.4%) did not (Group II). One hundred and two Group I and 52 Group II patients were evaluable for analysis. Median follow-up was 78.0 months for Group I and 60.0 months for Group II. Despite a preponderance of poor prognostic factors in Group II, no significant difference in local failure was seen. A component of local failure was seen in 6 Group I patients (6.0%) and 4 Group II patients (7.7%), p = 0.74. Distant failure, reflecting more advanced disease, was higher in Group II (19.2%) than in Group I (9.0%). Late complications included rectal bleeding/proctitis in 18.6% of Group I patients and 3.8% of Group II patients (p = 0.01). Overall, grade 2 complications occurred in 27.5% and 15.4% of Group I and II patients, respectively (p = 0.09). No difference in frequency of grade 3 complications was evident. Based on this retrospective study, intracavitary vaginal cuff boost after surgery and postoperative external beam radiation therapy does not appear to improve local control in early endometrial adenocarcinoma. Its possible effect on complication rates is uncertain.