Assessing the Under-Estimation of Nodal Tumor Burden by using 68GA PSMA and 11C-Choline PET/CT Scan

Our scanning technology has improved, especially in the last five years.  We need sensitive and accurate scans to be able to understand and respond appropriately to our prostate cancer.  This is especially true when prostate cancer recurs.

The technology, PET/CT exemplifies one of the most sensitive of the diagnostic modalities we have to assess the spread of recurrent prostate cancer. 

However, there is an assumption that even PET/CT, despite its sensitivity, still under-estimates the actual tumor burden. There is an additional hypothesis that the under estimation of tumor burden increases progressively by the number of positive nodes that are visualized by preoperative imaging.

A study that included 525 men who received lymph node surgery for recurrent prostate cancer diagnosed by PET/CT scan using either 11C-choline (n=356; 68%) or 68Ga-PSMA (n=169; 32%) confirmed the underestimation of positive nodes by PET/CT. 

The study showed that there was under-estimation with both tracers, but the under-estimation was even larger with 11C-Choline as compared to 68Ga-PSMA. 

In conclusion, the study showed that PET/CT scan significantly under-estimates the real tumor burden of prostate cancer nodal recurrence. In particular, the higher the number of positive spots, the higher the number of positive nodes that are missed by pre-operative PET/CT imaging. This under-estimation is greater with 11C-Choline compared to 68Ga-PSMA. 


Joel T. Nowak, MA, MSW wrote this Post.  Joel is the CEO/Executive Director of Cancer ABCs.  He is a Cancer Thriver diagnosed with five primary cancers - Thyroid, Metastatic Prostate, Renal, Melanoma, and the rare cancer Appendiceal cancer.