The successful management of two pregnancies with wild type metastatic gastrointestinal stromal tumors

Aim:  To discuss the management of the uncommon situation of metastatic gastrointestinal tumour coexisting with pregnancy. Method:  We describe two cases of women with metastatic gastrointestinal stromal tumor (GIST) who successfully achieved a full-term pregnancy without complications and with the delivery of healthy infants. In both cases, treatment with imatinib mesylate was withheld during pregnancy because of its unknown effects and questionable safety for the developing fetus. The available data in the medical literature regarding the use and safety of imatinib and pregnancy are reviewed. We also examine whether the knowledge of the exon mutational status would have influenced treatment decisions. Results:  Both women had wild type GIST, but with different tumor growth characteristics, treatment responses and outcomes. The first patient deferred imatinib therapy to fall pregnant and her disease progressed rapidly off treatment. The second patient had a more indolent GIST where active surgical management allowed her to experience a long durable clinical response. She potentially belongs to a pediatric subgroup which carries a better prognosis despite being off imatinib. Conclusion:  While we have successfully managed two pregnant women with metastatic GIST, the issue of initiating imatinib therapy in treatment-naive women, and treatment interruption in women already on therapy, remain difficult areas. Patients and their partners need to make an informed choice regarding the associated risks and the potential long-term sequelae if pregnancies are contemplated. Further research into the natural history of wild type GIST and how to tailor subsequent treatment are needed.