Vaginal brachytherapy alone: An alternative to whole pelvis radiation for early stage endometrial cancer

Vaginal lymphatic channel location and its implication for intracavitary brachytherapy radiation treatment

PURPOSE

In vaginal intracavitary brachytherapy using cylindrical applicators, it is common to prescribe dose to a depth of 0.5 cm to cover the lymphatic channels. However, the actual depth of the lymphatics within the vaginal wall has never been determined. In this study, we examined the depth distribution of lymphatics lying beneath the mucosal surface of the vagina.

METHODS AND MATERIALS

Between January 24, 1996 and October 27, 2003, 31 patients underwent full-thickness vaginal biopsy or partial resection for both benign and malignant disease. In addition, in February 2004, vaginal samples from two autopsy specimens were stretched and pinned for formalin fixation and slide production. Forty-five slides of both stretched and nonstretched vaginal tissue were stained with D2-40 monoclonal antibody lymphatic endothelium marker. The percentages of lymphatics located within 1, 1-2, 2-3, and 3-4mm were calculated for all slides.

RESULTS

For the nonstretched samples, the percentages of lymphatics located within 1, 1-2, 2-3, and 3-4mm were 50.5%, 30.7%, 11.9%, and 6.9%, respectively. For the stretched samples, the percentages of lymphatics located within 1, 1-2, 2-3, and 3-4mm were 44.0%, 33.8%, 18.8%, and 3.4%, respectively. The differences of lymphatic percentages within and superficial to 1mm (p=0.60), 1-2mm (p=0.85), 2-3mm (p=0.89), and 3-4mm (p=0.99) were not statistically significant between the stretched and nonstretched states.

CONCLUSIONS

Our results show that approximately 95% of vaginal lymphatic channels are located within a 3mm depth from the vaginal surface. This suggests that dose prescribed to a depth less than 0.5 cm may be adequate and could permit treatment with less normal tissue toxicity in certain clinical situations.

American Brachytherapy Society survey regarding practice patterns of postoperative irradiation for endometrial cancer: current status of vaginal brachytherapy

PURPOSE

To survey the current postoperative recommendations for radiotherapy (RT) in patients with endometrial cancer, with an emphasis on vaginal brachytherapy (VBT).

METHODS AND MATERIALS

In August 2003, a 32-item questionnaire was mailed to a random sample of 2396 members of the American Society for Therapeutic Radiology and Oncology and the American Brachytherapy Society. The sample excluded members-in-training, physicists, and non-U.S. members. A follow-up mailing was conducted in November 2003. Those who had not treated any patient in the previous year for endometrial carcinoma were instructed to indicate so at the beginning of the questionnaire and return it without responding to any other item. Responses were tabulated to determine the relative frequency distribution.

RESULTS

of the 2396 surveys sent out, 757 were returned, for a response rate of 31.6%. Of those who responded, 551 (72.8%) had performed postoperative irradiation for endometrial cancer and were included in this study. Of the 551 respondents, 99.8% had delivered external beam RT to some endometrial cancer patients. An increasing trend was found toward referrals for VBT; 91.5% of those who treated endometrial cancer performed VBT. The vaginal target most often irradiated was the upper vagina in 40.7%, upper 4-5 cm in 54.5%, and the entire vagina in 4.9%; 21.3% placed clips at the vaginal apex for applicator verification. The maximal dose to the bladder and rectum was recorded in 78.3% and 80.2% of patients, respectively. Of the respondents, 40% did not use low-dose-rate (LDR) VBT. The two most common LDR applicators were Delclos cylinders (29.7%) and Fletcher colpostats (29.3%). The mean boost dose delivered with LDR VBT when prescribed to the surface was 29.9 Gy and when prescribed to 0.5 cm was 23.8 Gy. When LDR therapy was used without external beam RT, the mean dose when prescribed to the surface was 56.8 Gy and when prescribed to 0.5 cm was 47.9 Gy. In 2002, 69.1% of respondents treated patients with high-dose-rate (HDR) VBT. Of the respondents, 90.6% used a single-channel vaginal cylinder, and 83.3% of cylinder users followed the curve of the cylinder to optimize dose, 67.9% adjusted the applicator position based on localization films, and 47% adjusted the applicator to be horizontal. The most common fractionation scheme when using HDR VBT as a boost was 5 Gy in three fractions prescribed to 0.5 cm (42.9%). The most common fractionation scheme used with HDR without external beam RT was 7 Gy in three fractions prescribed to 0.5 cm (41.8%).

CONCLUSION

VBT is a common recommendation for postoperative adjuvant therapy for endometrial cancer. HDR appears to be the most popular approach, with a wide variety of dose fractionation schemes reported. Additional study is warranted to help define the ideal use of VBT.