Head and Neck Tumor Control Probability: Radiation Dose-Volume Effects in Stereotactic Body Radiation Therapy for Locally Recurrent Previously-Irradiated Head and Neck Cancer: Report of the AAPM Working Group

Abstract

Purpose: Stereotactic body radiation therapy (SBRT) has emerged as a viable reirradiation strategy for locally recurrent previously-irradiated head and neck cancer. Doses in the literature have varied, which challenges clinical application of SBRT as well as clinical trial design.

Material & methods: A working group was formed through the American Association of Physicists in Medicine to study tumor control probabilities for SBRT in head and neck cancer. We herein present a systematic review of the available literature addressing the dose/volume data for tumor control probability with SBRT in patients with locally recurrent previously-irradiated head and neck cancer. Dose-response models are generated that present tumor control probability as a function of dose.

Results: Data from more than 300 cases in 8 publications suggest that there is a dose-response relationship, with superior local control and possibly improved overall survival for doses of 35 to 45 Gy (in 5 fractions) compared with <30 Gy.

Conclusion: Stereotactic body radiation therapy doses equivalent to 5-fraction doses of 40 to 50 Gy are suggested for retreatment.

Fig. 1.

Graphic depiction illustrating an association between dose, volume, and 1-year locoregional control after stereotactic body radiation therapy for recurrent head and neck cancer. Reproduced with permission from reference (11).

Fig. 2.

Pooled data from the literature reporting local control and dose at 1, 2, and 3 years, as shown. Each data point represents 1 data set, and doses are computed (via the linear-quadratic model) as “5-fraction equivalent total doses” (see text and Tables 1–3) (patient numbers of each study are in parenthesis in the keys of each figure panel). Vertical error bars are 68% binomial confidence intervals. Solid line is the logistic model; dashed lines are 95% confidence intervals for the dose-response.

Fig. 3.

Pooled data from the literature reporting overall survival and dose at 1 and 2 years, as shown. Each data point represents 1 data set, and doses are computed (via the linear-quadratic model) as “5-fraction equivalent total doses” (see text and Tables 1–3) (patient numbers of each study are in parenthesis in the keys of each figure panel). Vertical error bars are 68% binomial confidence intervals. Solid line is the logistic model; dashed lines are 95% confidence intervals for the dose-response.