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Researchers identify risk factors for soft tissue necrosis in OSCC
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A specific subset of patients with oropharyngeal squamous cell carcinoma who undergo transoral robotic surgery and postoperative radiotherapy demonstrated an increased risk for late consequential surgical bed soft tissue necrosis, according to results of a retrospective analysis.
Risk factors included tonsillar location, radiation dose to the surgical bed, depth of resection and severe mucositis, results showed.
John Lukens, MD, a radiation oncologist at The University of Pennsylvania, and colleagues sought to identify the frequency of and risk factors for the development of soft tissue necrosis (STN) in the surgical bed after completion of postoperative radiation therapy.
Researchers defined soft tissue necrosis as ulceration of the surgical bed that developed more than 6 weeks after postoperative radiation therapy and required opioids, biopsy or hyperbaric oxygen therapy.
The analysis included 170 patients with oropharyngeal squamous cell carcinoma (OSCC) who underwent transoral robotic surgery and postoperative radiation therapy between 2006 and 2012.
The cohort included 104 patients with tonsillar disease and 66 patients with base-of-tongue disease. All patients were followed for more than 6 months.
Overall, 47 patients (28%) were diagnosed with STN. Results showed tonsillar patients were more likely to develop STN than those with base-of-tongue OSCC (39% vs. 9%).
Among patients diagnosed with STN, median tumor size was 3 cm (range, 1-5.6) and median depth of resection was 2.2 cm (range, 1-5.1). The median radiation dose was 6,600 cGy and the median dose of fraction to the surgical bed was 220 cGy. Thirty-one (66%) of the patients received concurrent chemotherapy.
Median time to soft tissue necrosis after postoperative radiation therapy was 2.5 months, and the median time to resolution was 3.7 months.
Results of multivariate analysis identified several risk factors for STN, including tonsillar primary location (OR=4.73; P=.01), depth of resection (OR=3.12; P=.001), grade 3 acute mucositis (OR=3.47; P=.02) and total radiation dose to the resection bed (OR=1.51 per Gy; P<.01).
In May 2011, researchers avoided delivering more than 2 Gy per day to the resection bed mucosa. After that, only two of 26 (8%) patients developed STN. All cases were grade 2.
Disclosure: See the study for a full list of the researcher’s relevant financial disclosures.
Perspective
Back to TopBarbara Burtness, MD
Lukens and colleagues draw on a large institutional experience with transoral resection of oropharynx cancers to make a very useful observation about the risk for late soft tissue necrosis after transoral resection and post-operative radiation. They report a retrospective analysis of 170 patients who underwent transoral resection with postoperative radiation. Twenty-eight percent of patients developed soft tissue necrosis at a median time from the conclusion of post-operative radiation of 2.5 months. The authors identified a number of possible risk factors, including larger tumor size, deeper extent of resection, grade 3 mucositis during radiation, tonsillar primary site and higher radiation dose. Higher postoperative doses resulted when there were positive or close margins, or during radiation boost to sites of extranodal extension.
The use of transoral resection is on the rise in parallel with increasing numbers of oropharynx cancers resulting from HPV infection. Thus, it’s important for treatment teams to be aware of this risk, how soft tissue necrosis presents, and the possibility of using hyperbaric oxygen to treat it. These data may indicate that caution is warranted in using this approach — which is FDA approved only for T1 and T2 cancers — for larger cancers.
The ECOG-ACRIN Cancer Research Group is conducting a clinical trial of transoral resection followed by risk-based postoperative radiation. A central question of the trial is whether patients with negative margins and no or minimal extranodal extension can achieve comparable cure and superior functional recovery if the postoperative therapy is delivered to 50 Gy rather than 60 Gy. Based on these data, a lower rate of soft tissue necrosis might be a further benefit of deintensifying adjuvant therapy. Pending the results of that trial, judicious patient selection based on T stage and preoperative evidence for extranodal extension — and vigilance for this complication — are warranted.
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