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

Abstract

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 = 33; 41.8%), inconsistently shrinking LN with temporary enlargement limited to the first week (n = 14; 17.7%), or also during the subsequent weeks (n = 32; 40.5%). Nodal density at planning is highly predictive of group assignment, with a larger mean density for consistently over inconsistently shrinking LNs (p = .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.

Characteristics and kinetics of cervical lymph node regression after radiation therapy for human papillomavirus-associated oropharyngeal carcinoma: Quantitative image analysis of post-radiotherapy response

“…On multivariate analysis, larger (higher volume and short-axis diameter) nodes with a greater hypodense/lipid component and more heterogeneous nodes (greater HU standard deviation) were associated with reaching a <1 cm short-axis diameter. The findings of this study are concordant with those determined by Sanguineti et al who investigated oropharyngeal carcinoma nodal response patterns during RT and identified initial nodal CT metrics correlated with nodal volumetric behavior, one of the most consistent of which was CT nodal density [21]. …”

“…In addition, the proportion of soft tissue volume decreased, while the hypodense/lipid, fluid, and enhancement/calcification components increased (Fig. 2b), the latter of which has been observed in other studies [21, 22]. One interpretation of these findings is following radiation, sterilized lymphoid and tumor components are gradually replaced to by acellular scar tissue that facilitates fluid, hypodense debris, and mineral entrapment.…”

Nodal response after 46 Gy of intensity‐modulated radiotherapy is associated with human papillomavirus–related oropharyngeal carcinoma

“…An explanation for the difference between these results could be that HPV‐positive tumors have a more rapid early response after radiotherapy followed by tapered response such that it may take longer for HPV‐positive nodes to regress. Other studies performed weekly CT scans to measure the volume of positive lymph nodes . They found that in HPV‐positive patients with node‐positive OPSCC, spontaneous shrinkage was seen before radiotherapy, during treatment enlargement of nodes was seen, and shortly after treatment there was a poor response on IMRT (25.3% failed to show complete response after 12 weeks).…”

“…Other studies performed weekly CT scans to measure the volume of positive lymph nodes. 26,27 They found that in HPV-positive patients with node-positive OPSCC, spontaneous shrinkage was seen before radiotherapy, during treatment enlargement of nodes was seen, and shortly after treatment there was a poor response on IMRT (25.3% failed to show complete response after 12 weeks). This finding suggests that complementary neck dissection still seems necessary for a subgroup of these patients.…”

Technical guidelines for head and neck cancer IMRT on behalf of the Italian association of radiation oncology - head and neck working group

“…Most patients undergoing RT ± CT for HNC may lose a significant proportion of their weight (on averages 6% to 12% of pre-treatment body weight [ 68 ]) during a 7-week course. Sometimes, large nodal masses show a dramatic shrinkage [ 69 ]; especially when adjacent to surrounding normal structures (cord, parotids), the dose distribution during treatment may deviate significantly during treatment compared to initial planning [ 70 ]. Finally, it has been shown that almost all OARs undergo significant changes during treatment, with about 30% of shrinkage for major salivary glands, 10% for muscles (with the exception of constrictors) and 15% increase for larynx and constrictors [ 71 ].…”