1090 - Variance in Practice Patterns among Radiation Oncologists Treating Oropharyngeal Cancers

Purpose/Objective(s): With the increase of HPV mediated (HPV+) oropharyngeal (OPX) cancers, many studies have attempted to de-escalate therapy given their favorable prognoses. While published studies evaluate dose-reduction, few trials describe volume reduction. We surveyed expert head and neck (H&N) radiation oncologists who treat oropharyngeal cancer to better understand practice patterns to inform future clinical trial design.

Materials/Methods: Head and neck radiation oncologists were identified from the NRG Oncology’s H&N steering committee, the American Radium Society’s H&N guidelines committee, and the ASTRO education and scientific committees. Treatment of =12 cases of non-cutaneous H&N cancer within the last year was required. Participants were contacted via email with a link to an anonymous data collection web application survey comprised of 25 questions. Results were compared using data collection web application statistics and chi-square tests.

Results: 55 H&N radiation oncologists participated in the survey (36%) representing 41 institutions. 3 were excluded due to inadequate case volume or inability to verify professional affiliation. Most physicians treat definitively to either 69.96 or 70 Gy in 33 to 35 fractions (96% HPV+, 98% HPV-). Average CTV expansion is 3.6 mm. Yet, CTV expansions for HPV+ OPX vary considerably with 48% of responders expanding 0-3mm (19% of using 0mm CTV, 29% using 3mm, 40% using 5mm, and 6% using 8 mm). Additionally, 13 physicians (25%) use a smaller CTV expansion for HPV+ OPX lymph nodes while 39 (75%) use the same expansion. PTV expansions were uniform with 90% of responders using a 3 mm expansion regardless of HPV status. In the HPV- postoperative setting, 96% of responders treat to 60 Gy. In contrast, in the HPV+ postoperative setting 52% treat with 60 Gy whereas 35% use only 50 Gy (p<0.05), with multiple respondents justifying dose-reduction with recently published ECOG 3311. In HPV+ OPX, the most common indications for postoperative radiation include positive surgical margins (SM) and extranodal extension (ENE) (100%), pT3-4 (98%), = 2 involved nodes (92%), perineural invasion (77%), and lymphovascular invasion (62%). The addition of chemotherapy to postoperative radiation was most indicated for + SM and ENE (98% HPV+, 100% HPV-) as well as = 5 involved nodes (25% HPV +, 29% HPV -). 96% of responders prefer concurrent cisplatin when warranted (75% weekly; 21% high dose). For cisplatin-ineligible patients with HPV- H&N cancer, carboplatin and paclitaxel (59%) is preferred over cetuximab (18%), and single-agent carboplatin (16%). For cisplatin ineligible HPV+ patients, cetuximab (23%) use is slightly higher.

Conclusion: There is significant variation and lack of consensus in treatment patterns for oropharyngeal cancers among institutions. Given that head and neck radiation oncologists often reside at specialized academic centers, these results have implications for both resident training and patient outcomes.