PET Scan Negativity Post Treatment In DLBCL May Not Indicate A Cure

Diffuse Large B-Cell Lymphoma (DLBCL) is an aggressive Non-Hodgkin’s lymphoma. Previous work has suggested that a negative FDG-PET/CT scan, following chemotherapy with curative intent, indicated a cure. However, the understanding that a negative PET post-treatment indicates that no further PET scans are needed, has not yet been accepted as a standard of care. We reviewed the medical records of DLBCL patients with negative post-treatment PET scans in order to evaluate if further PET scanning is superfluous and that the treatment has effected a cure.

A list of DLBCL patients diagnosed and treated at JSUMC from 2000 to 2010 was obtained from the Tumor Registry. Patient health information was reviewed using electronic as well as paper records.

A total of 133 DLBCL patient charts were reviewed and only 40 had complete PET scan records available at the time of study. Thirteen of the 40 fit the criteria of a negative post-treatment PET scan. Sixty-nine percent (9/13) were males and 31% (4/13) were females. The average age at diagnosis was 61 years. Seventy-seven percent (10/13) had a complete response and did not relapse based on their subsequent PET scan reports. Twenty-three percent relapsed after 14, 22, and 25 months, respectively (3/13, 95% confidence interval: [5%, 54%]). The mean (standard deviation) annual number of PET scans was 1.65 (0.68). The frequency ranged from 0.55/year to 2.67/year.

Three of 13 DLBCL patients eventually relapsed after a negative post-treatment PET scan. This study suggests that careful monitoring of DLBCL patients who have negative PET scans is needed after treatment. Further studies need to be done to confirm the time period a PET scan may be most effective in restaging the disease.

No relevant conflicts of interest to declare.