Radiotherapy plays an important role in the treatment of anal cancer, but many female survivors treated with pelvic radiotherapy develop long-term sexual problems. A new study shows that it is possible to reduce the dose of radiation reaching the bulboclitoris (clitoris and vestibular bulbs), which would be expected to reduce this adverse effect.
Although the study found that reshaping radiotherapy to avoid the bulboclitoris is possible, the team noted, "We do not have clinical and patient-reported outcomes with which to validate our hypothesis that there is a clinically meaningful relationship between dose to the bulboclitoris and female sexual outcomes."
Nevertheless, the authors say the work is important. An expert not involved with the research applauded the authors for their work, which opens up a new approach. To date, much of the research on the impact of radiotherapy on female sexual health has "focused on the vagina, mainly with treatment sequelae of vaginal stenosis and dyspareunia," commented Jennifer Wo, MD, an associate professor of radiation oncology at Harvard Medical School and Massachusetts General Hospital, Boston.
"This research represents an important step in establishing an accurate anatomic definition of the bulboclitoris for radiotherapy," said lead author Deborah C. Marshall, MD, radiation oncology resident at the Icahn School of Medicine at Mount Sinai, New York City. "It provides critical data supporting further clinical investigation into avoidance of the bulboclitoris anatomy with the potential to improve important and largely overlooked sexual outcomes for female patients.
"Accurate anatomic delineation is critical when considering evidence-based approaches to reducing toxicity after radiotherapy. The bulboclitoris, the female anatomic organ responsible for arousal and orgasm, has yet to be fully defined in the radiotherapy literature," she said.
Marshall told Medscape Medical News that because pleasurable sexual experiences are an essential aspect of the quality of life across a person's life span, including cancer survivors, "accurate definition of anatomic correlates of female sexual arousal and orgasm in radiotherapy is important and long overdue."
The study was presented during a poster session at the annual meeting of the American Society for Radiation Oncology, which was held online because of the COVID-19 pandemic.
Another study presented at the meeting found that sexual dysfunction is a common treatment-related problem observed across numerous cancer types; it has been reported by 89% of cancer survivors. However, most patients reported that their oncologist had not discussed the topic, and female patients were particularly unlikely to be asked about sexual dysfunction.
For the study, the team analyzed data from 20 female patients with anal cancer who had received chemoradiotherapy. The patients were divided into groups according to the radiation dose they received. Organs deemed to be at risk included the external genitalia (labia/fat/clitoral glans, body), the bulboclitoris (clitoral glans/body/crura, vestibular bulbs) and the nonoverlapping bulboclitoris and planning target volume (PTV) region.
The team then examined details of the radiotherapy that these women received and how much radiation reached the organs at risk. One analysis compared the impact of clitoris-sparing intensity-modulated radiotherapy (IMRT) to that of standard IMRT.
The researchers noted that the bulboclitoris occupies 20 cc and that the volume is largely distinct from the external genitalia (median dice similarity coefficients, <.05). Bulboclitoris-sparing IMRT was superior to standard IMRT in reducing the dose to the bulboclitoris and bulboclitoris PTV, demonstrating that the bulboclitoris can be contoured on radiotherapy planning imaging.
Approached for comment, Boston's Wo noted that practitioners are becoming more aware of the importance of proactively addressing female sexual health in the context of cancer survivorship.
"Much of the efforts to date have been focused on mitigating treatment-related side effects with introduction of sexual health counseling early in the patient's care, and early intervention with vaginal dilators," she told Medscape Medical News.
Wo added that she applauds the authors for looking beyond traditional frameworks of how radiotherapy can affect female sexual health and for demonstrating the feasibility of reducing the dose to the bulboclitoris without sacrificing tumor coverage.
"Future studies should look to establish correlation between reduction of RT dose parameters to the bulboclitoris to patient-reported improvements in sexual health," she said.
The study was supported in part by the National Institutes of Health, NRG Oncology, and the Patty Brisbane Foundation for Women's Sexual Health.
American Society for Radiation Oncology (ASTRO) 2020 Annual Meeting: Abstract 3471. Presented October 26, 2020.
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Cite this: 'Reshaping' Radiotherapy May Reduce Female Sexual Dysfunction - Medscape - Nov 05, 2020.