Study shows survival advantage with brachytherapy for primary vaginal cancer
Women with primary vaginal cancer (PVC) who received brachytherapy – either by itself or in combination with external beam radiation therapy (EBRT) – had higher median overall survival (6.1 years) versus patients who received EBRT alone (3.6 years). The results were from a Surveillance, Epidemiology, and End Result (SEER) database study of 2,517 vaginal cancer patients.1
“The magnitude of the survival advantage for brachytherapy was surprising,” says Andrew Orton, MD, a radiation oncology resident at the University of Utah, Huntsman Cancer Institute (HCI), Salt Lake City, UT, and principal investigator of the study. “The NNT – the number needed to treat – which is the number of patients we would need to treat with brachytherapy to prevent one death from vaginal cancer – was just nine patients. That’s pretty few considering how well brachytherapy is tolerated and it represents an absolute benefit of 10 percent.”
The strongest predictors for omission of brachytherapy for treatment of PVC were larger tumor size >5cm and higher FIGO stage, i.e., stage III and IVA disease.
“I think there is some reluctance to use brachytherapy in large and advanced stage tumors due to fear of fistula formation and a concern that with larger volumes you may cause more toxicity with the typically high brachytherapy doses,” Dr. Orton observes. “Paradoxically, we found that the patients who benefited the most were those with tumors larger than 5 cm and who had advanced FIGO stages.”
There were no patient demographics or tumor characteristics that favored use of EBRT alone.
Vaginal cancer is uncommon. In 2016, approximately 4,600 women in the United States will be diagnosed with vaginal cancer, resulting in about 950 deaths.2
“While primary vaginal cancer is relatively rare, the survival improvement we saw with brachytherapy is hard to ignore,” says David Gaffney, MD, study co-author and professor of radiation oncology at the University of Utah School of Medicine and Huntsman Cancer Institute. “A local recurrence is devastating, so to improve local control and improve survival is immensely important to that patient in front of you.”
The authors conclude that the use of brachytherapy as a boost or as definitive monotherapy in appropriately selected patients “should be encouraged for all suitable patients. Neither FIGO stage IVA disease nor large tumor size should be considered contraindications to BT.”
Declining brachytherapy utilization
While additional recent SEER studies3-4 have shown brachytherapy’s clinical value in cervical and endometrial cancer, the modality’s use has been declining in the United States over the last two decades.
“Brachytherapy is more challenging on the physician’s part and reimbursement hurts us too, because clinics are getting reimbursed pretty well for IMRT and other radiotherapies,” Dr. Gaffney notes.
As a radiation oncology resident, Dr. Orton adds that brachytherapy training in medical education is not highly emphasized.
“The number of required brachytherapy cases that the Accreditation Council for Graduate Medical Education requires us to participate in before we graduate is not particularly large,” he says. “If a resident isn’t enrolled in a fairly brisk implantation program, it’s hard to gain the confidence to start your own program.”
Fortunately for Dr. Orton, Huntsman Cancer Institute and its sister facility, Intermountain Medical Center (IMC), run robust brachytherapy training programs and perform a large volume of brachytherapy procedures, especially for gynecological cases.
“We do quite a few tandem-and-ovoid implants, both with and without interstitial needles, in addition to low dose rate and high dose rate brachytherapy implants for prostate cancer and breast brachytherapy as well, both here at HCI and at IMC,” Dr. Orton says. “I’ve completed just two years of advanced training and I estimate I have done about 25 implants. To graduate I would need to have performed just five interstitial implants, so we’re pretty fortunate here at Huntsman.”
- Orton A, Boothe D, Williams N, et al. Brachytherapy improves survival in primary vaginal cancer. Gynecol. Oncol. 141 (2016) 501-506.
- Han K, Milosevic M, Fyles A, et al. Trends in the utilization of brachytherapy in cervical cancer in the United States. Int J Radiat Oncol Biol Phys 2013;87:111-119.
- Acharya S, Perkins SM, DeWees T, et al. Brachytherapy is associated with improved survival in in operable stage I endometrial adenocarcinoma: a population-based analysis. Int J Radiat Oncol Biol Phys. 2015 Nov 1;93(3):649-57. Doi: 10.1016/j.ijrobp.2015.06.013. Epub 2015 Jun 15.