Response to Therapy Status Is an Excellent Predictor of Pregnancy-Associated Structural Disease Progression in Patients Previously Treated for Differentiated Thyroid Cancer

Abstract

Background:

Pregnancy may be associated with an increased risk of recurrence/progression of differentiated thyroid cancer (DTC). However, it is unclear if the impact of pregnancy would differ based on pre-pregnancy response to therapy status. The objective of this study was to investigate the risk of recurrence/progression of DTC, applying the response to therapy assessments to pre-pregnancy status as recommended by the 2015 American Thyroid Association thyroid cancer guidelines.

Methods:

This was a retrospective review of 235 women followed at Memorial Sloan Kettering Cancer Center for DTC who had a term pregnancy after initial treatment for DTC between 1997 and 2015.

Results:

Structural disease recurrence/progression after pregnancy was documented in 5% (11/235) of the patients. When evaluated 3–12 months after delivery, patients who had an excellent, indeterminate, or biochemical incomplete response before pregnancy continued to show no evidence of structurally identifiable disease. Conversely, in women with a structural incomplete response to therapy prior to pregnancy, structural progression (defined as ≥3 mm increase in the size of known disease or identification of new metastatic foci) was identified after delivery in 29% (11/38). However, additional therapy was recommended during the first postpartum years in only 8% (3/38) of those patients who had a structural incomplete response to therapy prior to pregnancy, while the remainder (92%) continued to be followed with observation.

Conclusion:

None of the patients with an excellent, indeterminate, or biochemical incomplete response to therapy prior to pregnancy developed structurally identifiable disease after a full-term delivery. Even though structural disease progression was seen in almost a third of the patients with known structural disease prior to pregnancy, only a minority of these patients had changes sufficient to warrant additional therapy. These data confirm that pre-pregnancy response to therapy status is an excellent predictor of pregnancy-associated disease progression in women previously treated for DTC.