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New study on the effects of radiation therapy offers a chance at a cure for patients with vulvar cancer.

Vulvar cancer is rare. According to the American Cancer Society, it accounts for only 0.7% of all cancers in women. However, its incidence has been gradually increasing over the past few decades with more than 6,330 estimated new cases in the United States in 2022.

Vulvar cancer affects the vulva, the external female reproductive genitalia, which consists of labia, the opening to the vagina and the clitoris. Patients with vulvar cancer find their treatment options quite limited compared to the available treatment of other cancers. Historically, surgery has been the first line of treatment, but this carries high risks when considering the negative impact it can have on patients’ quality of life.

“A significant proportion of patients with vulvar cancer present with extensive disease that is not amenable to surgery without requiring functionally compromising or disfiguring procedures that can have a huge impact on patients’ physical, mental and social well-being,” said Dr. Anupam Rishi, a resident in Moffitt Cancer Center’s Radiation Oncology Program.

What we have found is that these patients do really well with organ-sparing chemoradiation. And for patients who have a reoccurrence of cancer, at least we can first offer a chance at a cure without having to undergo extensive surgery.
Dr. Anupam Rishi, Radiation Oncology Program

Rishi emphasizes that more treatment options are needed for these patients, like radiation therapy, which can be a curative treatment leading to organ preservation, something that surgery doesn’t always offer. Additionally, with recent advancements in radiation techniques, Rishi says we can now safely target a tumor with a high radiation dose that is more precise and spares surrounding healthy tissues and structures.

“We were trying to see if a nonsurgical, organ-sparing treatment approach, like radiation, could be an equally efficacious treatment in vulvar cancer, in the same way it has been for other cancer sites, like the cancers of the anal canal, cervix or head and neck cancers,” Rishi said. “However, because of the rarity of this disease there is lack of evidence from clinical trials evaluating curative radiation therapy.”

To determine if radiation could lead to effective outcomes for this patient population, Rishi and Dr. Michael Montejo led a study in collaboration with multiple cancer centers in the United States and Canada to determine the efficacy, patterns of failure and long-term toxicity of high-dose radiation therapy for the primary treatment of vulvar carcinoma.

The DRIVE study, which stands for definitive radiation therapy for primary vulvar cancer, investigated treatment compliance, toxicity and patterns of failure for 90 patients, ages 32 to 93, who received definitive high-dose conformal radiation therapy as the first line of treatment between 2010 and 2020. Results were presented at the American Society for Radiation Oncology annual meeting.

The investigators found that definitive high-dose radiation therapy for vulvar cancer achieves high rates of local control, meaning the growth of the tumor could be controlled. They also saw complete response rates of greater than 80% and good compliance with acceptable, dose dependent, long-term toxicity.

Rishi says this study could offer a chance at a cure for patients without necessitating aggressive surgery. He added that a possible negative side effect includes vaginal stenosis, which is the narrowing and shortening of the vagina due to the formation of scar tissue. In the DRIVE study, researchers found that 39% of patients developed significant vaginal stenosis, which can cause decreased vaginal lubrication, difficulties in sexual intercourse and impact future gynecological care. Rishi stresses that this side effect is manageable using vaginal dilator therapy following radiation, which can reduce the incidence and severity of vaginal stenosis.

“We saw in our study that patients who used vaginal dilators didn’t suffer from vaginal stenosis as much as those who did not,” Rishi said. “It’s a concern with radiation therapy, but we found that it is preventable.”

For the long-lasting implications of this study, Rishi says he’s hopeful that this data will expand the guidelines for the treatment of vulvar cancer.

“Once we get more data from other institutions, I think the DRIVE study has potential to change the guidelines for these patients and keep radiation as one of the options of treatment,” Rishi said. “What we have found is that these patients do really well with organ-sparing chemoradiation. And for patients who have a reoccurrence of cancer, at least we can first offer a chance at a cure without having to undergo extensive surgery.”