Locoregional failures and their relation to radiation fields following stereotactic body radiotherapy boost for oropharyngeal squamous cell carcinoma

Abstract

Background To investigate the location of recurrences with respect to the radiation fields in oropharynx cancer after intensity‐modulated radiotherapy and stereotactic body radiotherapy (SBRT) boost. Methods Local and regional recurrences were delineated on diagnostic scans which were rigidly coregistered with treatment planning scans, then classified based on the location of the center of mass (COM) as well as volumetrically. Results In 195 patients, the 5‐year local and regional control were 90% and 93%, respectively. By COM, 76% of local recurrences were in‐field; 24% were out‐of‐field, significantly higher than 0%‐5% in the literature for conventional regimens (P < 0.01). Regional recurrences (19 in 12 patients) were largely within unirradiated neck levels (47%) and electively irradiated regions (42%). Conclusions The regimen with biological equivalent dose intensification provides excellent overall and in‐field local control. The highly conformal boost technique was, however, associated with increased out‐of‐field local failure.

Long-term outcomes following stereotactic body radiotherapy boost for oropharyngeal squamous cell carcinoma

“…Thus, the total treatment time for the regimen is approximately 5 weeks. We regard this SBRT boost treatment schedule as a local dose intensification since the calculated biologically effective dose (including reduced treatment time) delivers up to 30.3 Gy (a/b = 10) higher biologically effective dose than a 7-week conventional IMRT regimen for rapidly proliferating tumors [18,19] (equation provided in supporting information). However, transforming this schedule into an equivalent dose in 2-Gy fractions, which does not account for overall treatment time, EQD2 is 67 Gy (a/b = 10).…”

“…A description of disease recurrences and subsequent treatment is provided in supporting information Table S1. A detailed analysis of the location of local and regional recurrences with respect to the radiotherapy fields has previously been published [18].…”

Stereotactic radiotherapy as planned boost after definitive radiotherapy for head and neck cancers: Systematic review

“…The countries represented in this study were Korea ( n = 1), Japan ( n = 1), China ( n = 1), Taiwan ( n = 1), India ( n = 1), Mexico ( n = 1), United States ( n = 2), and Netherlands ( n = 1) 18–26 . Overall, studies ranged from the years 2006–2020, with a median follow‐up time range from 8–56 months.…”

“…PFS rates were 80%–98% at 1 year, 70%–90% at 2 years, and 70%–90% at 3 years. LRFS was reported in four studies as follows: 91% at 1 year, 22 96% at 2 years, 22 82% at 3 years 18 85% in 4 years, 27 and 84% at 5 years 18 5.…”

The Evolving Role of Stereotactic Body Radiation Therapy for Head and Neck Cancer: Where Do We Stand?

“…Following this, they implemented the same treatment for cases of T1-2 and selected small T3, N0-N2 OPC. They documented the incidence of treatment failure, treatment results, and long term treatment related toxicity in a group of 195 patients who received treatment between 2009 and 2016 [52,53]. The reported 5 year LC and regional control (RC) rates were 90% and 93%, respectively.…”