KEY TAKEAWAYS
- The study aimed to investigate novel dosimetric predictors of ARD in head and neck radiotherapy, examining clinician-rated and PRO.
- Researchers noticed significant associations between skin dose-volume parameters correlated with acute radiation dermatitis, emphasizing the need to minimize skin exposure; further investigation is ongoing.
Acute radiation dermatitis (ARD) is a common side effect of head and neck cancer (HNC) radiotherapy (RT), yet reliable dosimetric predictors remain elusive. Additionally, data on the association between dosimetric factors and patient-reported outcomes (PRO) of ARD are limited.
Beverly Levine and the team aimed to identify dosimetric predictors of clinician-rated ARD in HN RT and explore their association with PRO measures of ARD.
They performed an inclusive analysis in this secondary analysis of a pilot study (NCT04173247), which included 24 patients receiving at least 60 Gy of radiation therapy. Dosimetric predictors of ARD were examined, with dermatitis assessments conducted at baseline, weekly during RT, and at 1-month post-RT using clinician-rated (CTCAE v5.0) and PRO measures (PRO-CTCAE v1.0 and Dermatologic Life Quality Index [DLQI]). The skin, defined as a ring-like structure comprising the inner 5 mm of the external contour generated by the treatment planning system, excluding bolus (if applicable), was analyzed.
The volume of skin (cm3) receiving a specified dose (V[x] Gy) was calculated in 5-Gy increments between V30-V70 Gy. For each parameter, the volume of skin was compared between patients who did and did not develop each RD outcome: CTCAE G2+ RD, PRO-CTCAE G2+ radiation skin reaction (RSR), or clinically significant 4-point increase from baseline DLQI score (DLQI4+).
Median RT dose administered was 68 Gy (range 60-70) in 28-35 fractions, with treatment encompassing bilateral neck (n=19), unilateral neck (n=2), or primary site alone (n=3). Sixteen patients received definitive treatment, while 8 underwent postoperative therapy; concurrent chemotherapy was administered to 18 patients. Clinician-rated CTCAE G2+ ARD was observed in 16 out of 24 patients, PRO-CTCAE G2+ RSR in 18 out of 24, and DLQI4+ in 13 out of 24.
Skin V40-V55 correlated with DLQI4+, and various skin dose parameters were linked to ARD at different significance levels. Skin dose exhibited significant associations with stage (I-II vs. III-IV), nodal classification, extent of neck target, and concurrent chemotherapy. However, skin dose-volume metrics showed no association with treatment group, intent (definitive vs. postoperative), age 65+, BMI category, diabetes, tumor classification, or primary site.
The study concluded that multiple skin dose-volume parameters correlated with clinician-rated and PRO ARD outcome measures during head and neck radiotherapy (HN RT). They emphasized the importance of including the skin as an organ at risk and minimizing its exposure to mitigate the risk of moderate to severe ARD.
The findings necessitate further validation and could aid in identifying high-risk patients for future studies on ARD. The trial was sponsored by Wake Forest University Health Sciences.
Source: https://astro.confex.com/astro/hncs2024/meetingapp.cgi/Paper/59506
Clinical Trial: https://clinicaltrials.gov/study/NCT04173247
Levine B, Frizzell B.A, Porosnicu M, et al. (2024). “Dosimetric Predictors of Clinician-rated and Patient-reported Radiation Dermatitis in Head and Neck Cancer: Exploratory Analysis of a Prospective Pilot Study.” Presented at MHNCS 2024 (Abstract 198).
