Sunday, July 24, 2016

More important points to keep in mind when reading scans!!!!

We have already learned that responses to immunotherapy may be delayed; that there can be pseudoprogression....where tumors look as if they have grown due to the influx of fighting T cells and inflammation and mayhem that causes.  But now, there's this:

Residual FDG-PET metabolic activity in metastatic melanoma patients with prolonged response to anti-PD-1 therapy.  Kong, Menzies, Saunders, et al. Pigment Cell Melanoma Res. 2016 Jun 22. 

FDG-PET scans were performed on twenty seven patients with unresectable stage IIIC or IV melanoma after prolonged treatment with anti-PD-1 antibodies to examine the hypothesis that patients with prolonged response to treatment may have metabolically inactive lesions by FDG-PET. Scans were performed at a median of 15.2 months (range 12-29 months) after starting treatment. Overall 15/27 (56%) patients had a positive FDG-PET scan. Eight patients with positive scans underwent biopsy; 5/8 (62%) were melanoma and 3/8 (38%) were immune cell infiltrates. Of the 12 patients with negative FDG-PET scans, 6 had residual CT visible lesions, 5 have ceased treatment and none have recurred with follow up of 6 to 10 months. Patients with residual metastases after a prolonged period without progression on anti-PD-1 therapy may have metabolically inactive lesions. Isolated metabolically active lesions in clinically well patients may reveal immune cell infiltrates rather than melanoma.

 FYI! - c

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