Lymph nodes of patients with regional metastases from head and neck squamous cell carcinoma as a predictor of pathologic outcome: size changes at CT before and after radiation therapy

Abstract

Background and purpose: Viable tumor in a neck dissection specimen is important in predicting prognosis and directing treatment. Our purpose was to clarify the importance of size changes of regional metastases from head and neck squamous cell carcinoma on CT scans obtained before and after radiation therapy (RT) as a predictor of pathologic outcome.

Methods: Thirty-seven heminecks in 34 patients who underwent pre-RT CT, RT, post-RT CT, and post-RT neck dissection were reviewed. Thirteen hemineck specimens were pathologically positive. Decrease ratios of the largest axial dimension of the lymph nodes between the pre- and post-RT CT studies were calculated.

Results: Six of 37 heminecks had a decrease ratio greater than 50%. These yielded negative specimens after planned neck dissection. In two of 37 heminecks, the largest axial dimension of the largest node increased between studies, resulting in negative decrease ratio. One (decrease ratio, -20%) had a positive specimen, and the other (decrease ratio, -3%) had a negative specimen. No interval change in size in the largest node was noted in one of the 37 heminecks; its specimen was positive. Average decrease ratios were 41.2% (range, -3% to 62%) in the negative specimen group (n = 24) and 27.2% (range, -20% to 50%) in the positive specimen group (n = 13). Univariate analysis revealed that the decrease ratio was not a significant predictor of a positive surgical specimen (P =.154).

Conclusion: Heminecks in which the decrease ratio was greater than 50% tended to have a negative surgical specimen. However, this trend was not statistically significant.

Fig 1.

Images in a 46-year-old man with a carcinoma at the base of his tongue (T4N3[3, 3]). (The percentage decrease ratio was calculated as in follows: % decrease ratio = (1 - b/a) × 100, where a and b are the dimensions shown in images A and B, respectively. A, Pre-RT contrast-enhanced CT image reveals enlarged level 2 lymph nodes (N) on both sides. The one on the right measures 54 × 33 mm, and that on the left, 57 × 45 mm. The nodes contain focal areas of low attenuation. An infiltrative mass involves the lower part of the base of the tongue. B, Post-RT contrast-enhanced CT image shows a marked decrease in the size of the lymph nodes. The decrease ratio of the largest dimension of the nodes is 59% on the right and 51% on the left. The patient underwent planned post-RT neck dissection on both sides. The surgical specimens were negative on both sides.

Fig 2.

Images in a 64-year-old man with metastatic neck disease from an unknown primary squamous cell carcinoma (TXN2A). A, Pre-RT contrast-enhanced CT image reveals an enlarged (27 × 22 mm) level 2 lymph node (N) on the left. B, Post-RT contrast-enhanced CT image shows a small residual mass (arrow) (decrease ratio of the largest dimension of the node, 52%). The patient underwent left neck dissection after this study. The specimen from the left hemineck was negative.

Fig 3.

Images in a 52-year-old man with tongue base carcinoma (T2N2B). A, Pre-RT contrast-enhanced CT image shows the enlarged (34 × 24 mm) level 2 lymph node (N) on the right. The node contains a focal area of low attenuation. B, Post-RT contrast-enhanced CT image reveals a minimal decrease in the size of the lymph node (decrease ratio of the largest dimension of the node, 6%). The surgical specimen from planned post-RT neck dissection at level 2 of the right hemineck was positive.

Fig 4.

Images in a 78-year-old woman with pyriform sinus carcinoma (T2N2A). A, Pre-RT contrast enhanced CT image shows an enlarged (40 × 25 mm) level 4 lymph node (N) on the right. The nodal mass distorts the adjacent right internal jugular vein (J). B, Post-RT contrast-enhanced CT image shows a slight increase in the size of the lymph node (decrease ratio of the largest dimension, −20%). The internal attenuation is generally lower on this image than on the image in A. The specimen from the right hemineck was positive.