Jennifer Byrne , 2025-04-23 15:42:00
April 23, 2025
5 min read
Key takeaways:
- Anal cancer is rare, but incidence has increased steadily the past 2 decades.
- The guideline is intended to assist radiation oncologists with ‘very complicated’ radiation techniques for anal cancer treatment.
The American Society for Radiation Oncology has issued its first clinical guideline on the use of radiation therapy to treat adults with anal cancer.
ASTRO developed the guideline — published in Practical Radiation Oncology — in cooperation with ASCO and Society of Surgical Oncology.
Anal cancer is rare compared with colon or rectal cancers; however, incidence has increased steadily over the past 20 years, according to ASTRO.
An estimated 10,540 new cases are diagnosed each year in the United States, with twice as many cases among women than men, according to American Cancer Society statistics. Nearly 2,200 people die of the disease each year. Anal cancer is most prevalent among Black men and white women.
Most patients with anal cancer do not develop metastases, and locoregional disease is frequently curable.
The current standard of care is chemoradiation, rather than permanent colostomy. This approach has been linked to acute and chronic toxicities, but advances in radiation therapy have helped to reduce them.
The guideline is designed to advise clinicians about the highly precise radiation techniques required to treat anal cancer, according to Mary Feng, MD, FASTRO, vice chair of the guideline task force and professor of radiation oncology at University of California, San Francisco.
“Radiation treatment for anal cancer is very complicated, technically speaking,” Feng told Healio. “There’s high potential for even small variations in how it is performed [that could] mean the difference between cure and no cure for a patient, or high quality of life and poor quality of life. We thought it was particularly important to put out a guideline that’s very technically oriented but also considers the holistic patient.”
‘A massive team effort’
A multidisciplinary task force comprising radiation, medical and surgical oncologists, as well as a medical physicist and a patient representative, developed the guideline. ASTRO also partnered with Agency for Healthcare Research and Quality, which helped with a comprehensive comparative-effectiveness review.
“The guideline was a massive team effort,” Feng said.
The guideline addresses indications for radiation therapy, concomitant systemic therapy, and surgery for patients with localized anal squamous cell carcinoma. It also discusses optimization of dosing, radiation techniques/treatment planning and approaches to post-treatment care.
“The guidelines were developed around certain key questions — that’s the format ASCO and ASTRO guidelines are following to make them accessible,” Feng said. “We thought about what questions practitioners might have about the treatment of particular cancers, and part of the guidelines were based on answering those questions.”
Key questions answered
The first of the four key questions addressed in the guideline focuses on which patients can be treated with surgery alone, versus those who also require chemoradiation for cure and organ preservation.
“There are some patients who might be able to have just surgery alone,” she said. “Others might actually not need surgery.”
The second question considers which type of radiation to use. The guidelines specify that intensity-modulated radiation therapy is superior to conventional, 3-dimensional conformal radiation therapy.
“It’s quite clear now that intensity-modulated radiation is better, and most insurance companies do cover that now,” Feng said. “We thought it was very important to put that in the guideline just to be sure that if there were any holdouts, we could point to this guideline so that physicians don’t have to spend additional time on prior authorization to get this advanced technology covered.”
The third question addresses the specific radiation parameters and planning techniques recommended to balance optimal treatment with minimal short- and long-term adverse effects.
“There are many different dose parameters for different organs, including the genitalia, the intestines and the bladder,” she said. “These guidelines are set up to help people create often beautiful radiation plans that can both fully treat the cancer and avoid damaging normal tissue.”
The fourth question relates to surveillance for patients who have undergone treatment for anal cancer.
“This question is about what we do after treatment and how we make sure the cancer is gone,” Feng said. “It also considers the most logical, cost-effective and scientifically driven way to do that, in terms of what scans are done and how often they should be done.”
‘Guidelines are never the end’
Feng said she hopes the guideline will provide clinicians with the detailed recommendations needed to standardize complex treatments for anal cancer.
“It’s relatively rare, and when we have a very rare condition with complicated treatments, we really need to standardize these treatments,” she said. “We hope that through these guidelines, community radiation oncology centers can then turn these into planning directives or other templated materials so they’re not reinventing the wheel every time.
“We want clinicians to spend their time and energy on the important intricacies of decision-making, caring for the whole patient,” she added. “Hopefully, these guidelines can be used to template workflows by practicing oncologists in their medical centers for radiation oncology.”
Feng said she also supports the idea of templated planning directives to help guide treatment.
“These have started to gain traction in medical centers – they are directives that are made for each body part in each situation for someone with anal cancer,” she said. “There’s a standard, templated list of information about radiation dosages and administration so people don’t have to look it up in a book and manually write it out every time. Those types of templates are really important, and we hope that people will make more of them.”
The guidelines likely will evolve over time as new information becomes available.
“Guidelines are never the end of something — they’re really the beginning,” Feng said. “Since this is the very first guideline, we’re hoping it will highlight what we do know for sure about anal cancer, but also what we don’t know for sure.”
For example, knowledge remains limited on topics such as how to prevent vaginal fibrosis or retain sexual function.
“We don’t exactly know all those answers,” Feng said. “This guideline is intended not only to bring everyone to a certain level of quality and standardization, but also to show where the gaps in our knowledge exist, so that we can be motivated to fill in those gaps and improve patients’ lives.”
References:
For more information:
Mary Feng, MD, FASTRO, can be reached at mary.feng@ucsf.edu.
Sources/Disclosures
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Disclosures:
Feng reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.
