Volumetric change of human papillomavirus-related neck lymph nodes before, during, and shortly after intensity-modulated radiation therapy

Background. To assess volumetric changes of human papillomavirus (HPV)-related lymph nodes (LN) before, during, and after a course of intensity-modulated radiation therapy (IMRT) � chemotherapy. Methods. Each ''pathologic'' LN (� 1 cm) was contoured on the available diagnostic/planning CTs before, during each week, and after treatment. Results. Seventy-nine LNs in 50 patients were identified. Beyond the first week of treatment, 3 patterns of LN change were recorded: consistently shrinking LN (n ¼ 33; 41.8%), inconsistently shrinking LN with temporary enlargement limited to the first week (n ¼ 14; 17.7%), or also during the subsequent weeks (n ¼ 32; 40.5%). Nodal density at planning is highly predictive of group assignment, with a larger mean density for consistently over incon- sistently shrinking LNs (p ¼ .009). Also, this grouping predicts the response at the end of treatment. Conclusion. HPV-related LN behavior during IMRT is extremely variable but somewhat predictable on the basis of nodal density at planning. V C 2012 Wiley Periodicals, Inc. Head Neck 00: 000-000, 2012