Women with inoperable, early stage endometrial cancer tend to live longer if they are treated with brachytherapy with or without external beam radiation, according to new research that was presented at the 3rd ESTRO (European Society for Therapeutic Radiology and Oncology) Forum in Barcelona, Spain.
Brachytherapy is a type of internal radiotherapy that involves putting a radioactive source close to, or in the tumour. Although it has been used historically to treat inoperable endometrial cancer, there are no guidelines based on randomized evidence to support this approach.
“To our knowledge, this is the first population-based study to compare outcomes for patients who received brachytherapy, with or without external beam radiation, to those who did not receive brachytherapy and were treated with external beam radiation alone,” explained Sahaja Acharya, MD, a resident physician in the Radiation Oncology Department of Washington University in Saint Louis, Missouri. She and her colleagues analyzed data from the National Cancer Institute’s Surveillance, Epidemiology and End Results (SEER) database for 460 women in the United States who had been treated with radiation therapy between 1998 and 2011 for inoperable stage I endometrial cancer.
Usually, early stage endometrial cancer can be removed surgically and has a good prognosis. However, sometimes it is inoperable and this can be for a number of reasons, including if the patient has a number of other medical problems that would make an operation risky or if they are very overweight or obese. In these cases, radiotherapy is the only remaining treatment option and the average survival time is approximately 3 years.
Of the 460 women, 260 (56.5%) had been treated with external beam radiation alone, and 200 (43.5%) with brachytherapy, with or without external beam radiation. Younger women were more likely to receive brachytherapy.
The researchers found that brachytherapy was associated with a better overall survival. Death from any cause was 13% lower, with 60% of women who had been treated with brachytherapy alive 3 years after treatment; in comparison, 47% of women who had been treated with external beam radiation alone were alive 3 years after treatment. The researchers then matched women who received brachytherapy to those who did not receive brachytherapy based on age, grade, and year of diagnosis. After adjusting for these factors, they found the survival benefit persisted in favor of those who received brachytherapy.
In addition, deaths from endometrial cancer were lower after 3 years among the women treated with brachytherapy; 18% of women treated with brachytherapy died from their malignant disease, compared with 26% of women who had not received brachytherapy.
The median survival for all the women was 40 months. “These patients have many other medical problems and not only die from endometrial cancer, but also from causes other than cancer, such as cardiovascular disease,” Acharya said.
“These findings show that brachytherapy is associated independently with an improved overall survival 3 years after diagnosis for women with inoperable stage I endometrial cancer. All these patients should be considered for brachytherapy and it should be administered when feasible.”
Acharya pointed out that this population-based analysis shows an association between treatment with brachytherapy and better survival, but the study cannot show that brachytherapy is the cause of the better survival when compared with external beam radiation alone. Proof of causation would require a randomized controlled trial.