Evaluation of Metachronous Breast and Endometrial Cancers: Preroutine and Postroutine Adjuvant Tamoxifen Use.

BACKGROUND: The time interval between diagnoses of breast cancer (BC) and endometrial cancer (EC) is not well established in women with metachronous primary tumors. We sought to examine this interval and identify associations with treatment-related and clinicopathologic factors. METHODS: We identified 141 patients who developed both cancers during 1966 to 2013. Patients were divided into 2 groups: group 1, BC first, and group 2, EC first. Subanalysis performed of group 1 (59 patients) stratified around adjuvant tamoxifen use: pre-1990 BC diagnosis and post. RESULTS: Fifty-nine and 82 patients were in groups 1 and 2, respectively. The mean time interval was comparable (76 vs 74 months, P = 0.861). Subanalysis divided group 1 into pre- (n = 27) and post- (n = 32) 1990 and resulted in different mean time intervals between diagnosis of metachronous cancers (106 vs 50 months, respectively [P = 0.042]). Median progression-free survival (PFS) and overall survival (OS) for EC were longer in the pre group (PFS, 51 vs 26 months [P = 0.169]; OS, 59 vs 27 months [P = 0.190]). Median PFS and OS for BC were also longer in this group (PFS, 147 vs 109 months [P = 0.005]; OS, 166 vs 114 months [P < 0.001]). CONCLUSIONS: Our data indicate the mean time interval between the diagnosis of EC and BC was approximately 6 years. Disease-specific EC survival was worse for patients with a previous diagnosis of BC. Stratification around implementation of tamoxifen use shows comparable grade and stage but different time interval and survival, suggesting resulting effects from adjuvant therapy for BC. These results are useful in counseling women at risk.

6-Fluoro-6-deoxy-D-glucose as a tracer of glucose transport.

Glucose transport rates are estimated noninvasively in physiological and pathological states by kinetic imaging using PET. The glucose analog most often used is (18)F-labeled 2FDG. Compared with glucose, 2FDG is poorly transported by intestine and kidney. We examined the possible use of 6FDG as a tracer of glucose transport. Lacking a hydroxyl at its 6th position, 6FDG cannot be phosphorylated as 2FDG is. Prior studies have shown that 6FDG competes with glucose for transport in yeast and is actively transported by intestine. Its uptake by muscle has been reported to be unresponsive to insulin, but that study is suspect. We found that insulin stimulated 6FDG uptake 1.6-fold in 3T3-L1 adipocytes and azide stimulated the uptake 3.7-fold in Clone 9 cells. Stimulations of the uptake of 3OMG, commonly used in transport assays, were similar, and the uptakes were inhibited by cyclochalasin B. Glucose transport is by GLUT1 and GLUT4 transporters in 3T3-L1 adipocyte and by the GLUT1 transporter in Clone 9 cells. Cytochalasin B inhibits those transporters. Rats were also imaged in vivo by PET using 6(18)FDG. There was no excretion of (18)F into the urinary bladder unless phlorizin, an inhibitor of active renal transport, was also injected. (18)F activity in brain, liver, and heart over the time of scanning reached a constant level, in keeping with the 6FDG being distributed in body water. In contrast, (18)F from 2(18)FDG was excreted in relatively large amounts into the bladder, and (18)F activity rose with time in heart and brain in accord with accumulation of 2(18)FDG-6-P in those organs. We conclude that 6FDG is actively transported by kidney as well as intestine and is insulin responsive. In trace quantity, it appears to be distributed in body water unchanged. These results provide support for its use as a valid tracer of glucose transport.