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Postop Radiation Aids Survival In Some Endometrial Ca Patients


 

PHILADELPHIA — Adjuvant external beam radiation therapy with or without vaginal brachytherapy can lead to improved overall survival for some women with high-risk endometrial carcinoma, according to a study reported at the annual meeting of the American Society for Therapeutic Radiology and Oncology.

“Endometrial adenocarcinoma remains the most commonly diagnosed [gynecologic] malignancy in the United States, but optimal treatment for stage I and II disease remains controversial,” said Dr. Christopher M. Lee of the department of radiation oncology, Huntsman Cancer Hospital, Salt Lake City. He noted that selected high-risk subgroups have increased local-regional recurrence rates and decreased survival, but which of those patients might benefit from adjuvant radiation is still controversial.

In this retrospective analysis, Dr. Lee and colleagues utilized the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) registry database to identify women with stage IC/grade 3 and stage II endometrial carcinoma without N1 or M1 disease. Specifically, they extracted data from the SEER 11 registries and Alaska data set containing data on patients diagnosed between 1988 and 2001. They identified 4,010 patients—all of whom had undergone hysterectomy with bilateral salpingo-oophorectomy—and analyzed prognostic factors such as age, race, cancer stage, tumor grade, extent of surgery, and whether or not they had received postoperative external beam radiation therapy (EBRT) with or without brachytherapy. Of the patients, 31.3% had received EBRT and 26.2% had received EBRT plus brachytherapy. “It was interesting to us that 42.5% of this population had received no further adjuvant treatment,” Dr. Lee said.

A Kaplan-Meier analysis revealed that patients with stage II/grade 1 disease received no additional survival benefit from either EBRT or brachytherapy, alone or combined. However, patients with stage IC/grade 3–4, stage II/grade 2, and stage II/grade 3–4 disease all received additional benefit with EBRT plus or minus brachytherapy. “Of interest, there were significant improvements in overall survival between external beam radiation versus EBRT versus EBRT plus [brachytherapy] in both the stage IC high-grade and the stage II high-grade cohorts,” Dr. Lee said.

Further analysis revealed that older age, late diagnosis, black race, and no nodal exam at the time of hysterectomy all had a detrimental effect on survival. After controlling for these factors, the authors found that there was a significant overall survival advantage with EBRT plus or minus brachytherapy for patients with stage IC/grade 3–4, stage II/grade 2, and stage II/grade 3–4 disease, but not with stage II/grade 1 disease. Contrary to the prior results, there was no improvement in overall survival with the addition of brachytherapy to EBRT. These data show that “the improvement in overall survival is really due to the EBRT component” and not to the additional brachytherapy component,” Dr. Lee said.

Because of the retrospective nature of the trial, he cautioned against making too many conclusions about the data. “In the future, we would like to continue to look into and delineate the clinical and biological factors that would help us guide treatment and help us to account for the disparities we see between different patient cohorts, and to continue to develop a standardized and a risk-adaptive or stratified approach for adjuvant treatment for these patients,” Dr. Lee said.

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