Adjuvant High-Dose-Rate Brachytherapy Alone for Stage I/II Endometrial Adenocarcinoma using a 4-Gray versus 6-Gray Fractionation Scheme Marie Lynn Racine, M.D1 and Akila N. Viswanathan, MD, MPH1.

1Department of Radiation Oncology, Brigham and Women's Hospital/Dana-Farber Cancer Institute, Boston, Massachussets, United States, 02115

Material and Methods

The characteristics of the patients are presented in Table 1. The two groups were balanced with regard to median age, FIGO Stage, presence of lymphovascular invasion, and LND status. Slightly more patients in group I had LND but this was not statistically significant. In the 4-Gy/fx group, with a median follow-up (FU) of 17.3 months (range, 1.3-28.7), there were no vaginal recurrences (0/37). In the 6-Gy/fx group, with a median follow-up of 34.3 months (range, 2.1- 65.6), there were 2/34 (6%) vaginal recurrences (chi-square p=0.03), diagnosed 3 and 4 months after treatment.

Purpose/Objective

Conclusion

g

Adjuvant vaginal brachytherapy (VB) after a total-abdominal hysterectomy (TAH) for Stage I/II (occult) endometrial cancer reduces the risks of local recurrence. However, the optimal dose to be delivered is still under debate. It has recently been suggested that a smaller dose per fraction would help decrease vaginal stenosis rates, mucosal atrophy and vaginal bleeding in a population diagnosed with low-risk endometrial cancer, compared to a higher dose per fraction regimen. After the 2005 publication of a trial from Sorbe showing lower vaginal stenosis rates in patients treated with 6 fractions of 2.5 Gy prescribed at 5 mm, this regimen was modified at BWH/DFCI to 4 Gy/fraction times 6 fractions prescribed at the vaginal surface.

The purpose of this study was to assess the risk of vaginal recurrence and compare two high-dose-rate (HDR) dose-fractionation schedules in patients with Stage I/II endometrial adenocarcinoma treated with a total-abdominal hysterectomy with or without lymph node dissection (LND) followed by adjuvant endocavitary vaginal brachytherapy alone.

From 2002 to 2007, 116 patients were treated with a TAH followed by HDR VB at the Brigham and Women’s Hospital. Of these 116, 29 were excluded because of Stage III disease (6), non- endometrioid pathology (21) or synchronous carcinoma (2). Seventy-one had full follow-up information available and were included in the analysis. Between August 2002 and August 2005, 34 patients were treated with 6 Gy times 5 fractions. Between April 2005 and March 2007, 37 patients were treated with 4 Gy times 6 fractions. A chi-square test was used to compare the recurrence rates in the two groups.

Group I

4 Gray/fraction

Group II

6 Gray/fraction

Median age63

(range: 46-81)

68

(range: 48-86)

Number of patients

(%)

Number of patients

(%)

Status of Nodal dissection

Nodal sampling

Complete nodal dissection

No Nodal dissection

Lymphovascular invasion

Present

Absent

8 (22)

26 (70)

3 (8)

5 (14)

32 (86)

9 (28)

16 (47)

9 (25)

3 (9)

31 (91)

FIGO Stage

IA

IB

IC

IIA

Occult IIB

1 (3)

23 (62)

8 (21)

1 (3)

4 (11)

1 (3)

20 (59)

8 (23)

4 (12)

1 (3)

Grade

1

2

3

13 (35)

17 (46)

7 (19)

6 (18)

22 (64)

6 (18)

In this series, 4 Gy/fraction prescribed to the vaginal surface yields an excellent outcome for patients diagnosed with early-stage endometrial adenocarcinoma treated with vaginal brachytherapy only, and is comparable to the higher dose per fraction regimen. Long-term follow-up is needed in order to further assess the toxicities including vaginal stenosis, and the long term vaginal recurrence rate.

Table 1. Characteristics of patients

Results