UC Davis researchers have shown that radiation therapy before surgery improves overall survival for patients with soft tissue sarcomas. This pre-surgical, or neoadjuvant, radiotherapy allows surgeons to get better margins around tumors and remove even microscopic cancer tissue more often. The study was published recently in the Annals of Surgical Oncology.
"It’s been thought for a while that pre-operative radiation increases the incidence of a complete cancer resection, or removal, in patients,” said first author and third-year general surgery resident, Alicia Gingrich. “This is the first time anyone has shown that pre-operative radiation actually generates high complete resection rates and better patient outcomes.”
Soft tissue sarcomas are relatively rare tumors often treated with radiation and surgery. However, clinicians have been split on whether radiotherapy should be conducted before or after surgery, or not at all.
To better understand the significance of radiotherapy timing, the team, led by Robert Canter, associate professor in the UC Davis Department of Surgery, studied nearly 28,000 sarcoma patients from the National Cancer Database. Among this group, 11.8 percent received radiotherapy before surgery, 37.2 percent received it after, and 51 received none at all.
The team found that 90.1 percent of patients who received pre-surgical radiation had more comprehensive, complete tumor removal, compared to 74.9 percent of those who received post-surgical radiotherapy.
“With a complete tumor removal, nothing is left, not even microscopic,” said Gingrich.
Other, less comprehensive tumor removal procedures can leave microscopic cancer or even visible disease. These options might lead to increased post-operative radiation to root out any remaining cancer, but this can be associated with long-term problems such as scarring, tissue fibrosis, and even lymphedema.
Complete tumor removal and both pre-operative and post-operative radiation all predicted improved overall survival for the entire cohort, but Gingrich and colleagues observed higher rates of complete tumor removal among patients who received preoperative radiation. In addition, the improved surgical margins associated with neoadjuvant radiation may have boosted survival for patients with high-grade sarcomas.
While pre-operative radiation can cause acute side effects, it does not have the long-term, chronic effects associated with post-operative radiotherapy. Pre-operative radiation also offers the dual advantages of shrinking tumors and hardening the outer “shell” that encases most sarcomas.
“Sarcomas are surrounded by a pseudocapsule, which is a layer of cells around the tumor that aren’t necessarily malignant but have been pushed on by the tumor,” said Gingrich. “There’s often some microscopic evidence of disease past this pseudocapsule. Radiation therapy causes the capsule to thicken and prevent cancer cells from going past.”
The authors believe these results will help guide clinicians and tumor boards as medical, surgical and radiation oncologists and others discuss the best combinations of therapies for sarcoma patients.
“Neoadjuvant radiotherapy leads to more optimal surgical tumor removal for patients with soft tissue sarcomas,” said Gingrich. “I think this will influence clinical decision-making at referral centers for sarcoma patients where these tumor boards come together.”
Other authors included Sarah B. Bateni, Arta M. Monjazeb, Morgan Darrow, Steven W. Thorpe, Amanda R. Kirane and Richard J. Bold, all from UC Davis.
This study was funded, in part, by the Dr. Mark Starr Family Fund.