Tamoxifen Induced Pancreatitis in a Non-Diabetic Patient with Hypertriglyceridemia

Introduction : Tamoxifen is a selective estrogen receptor modulator (SERM) used in breast cancer treatment. It interferes with triglyceride metabolism causing hypertriglyceridemia and can precipitate pancreatitis. We report a case of a non- diabetic middle-aged woman with a history of mild hypertriglyceridemia who presented with acute pancreatitis while on chronic tamoxifen treatment for breast cancer.

Case Description : 48-year-old Latin American woman with a history of hypertriglyceridemia, triple positive left sided breast cancer on active chemotherapy presented to the emergency department with abdominal pain.
Patient was diagnosed with acute pancreatitis with serum triglycerides greater than 4425 mg/dl  serum lipase 188U/l ,CT abdomen revealed proximal peripancreatic inflammation. Four years prior to the presentation she was diagnosed with mild hypertriglyceridemia managed with lifestyle modifications. Patient has a family history notable for hypertriglyceridemia in mother and sister. Two years later she was diagnosed with breast cancer, which required surgery and chemotherapy with tamoxifen (baseline triglycerides were 750 mg/dl). A lipid profile obtained three months after the initiation of tamoxifen therapy revealed triglycerides 3143 mg /dl. Patient was started on lipid lowering medication (Gemfibrozil 600 mg) and subsequent lipid profile was < 1000 mg/dl. It was decided to continue with Tamoxifen therapy while closely monitoring the lipid profile. She remained euglycemic throughout with HbA1c < 5.5. During the time of the pandemic, the patient was afraid to visit hospital for follow up appointments and eventually ran out of gemfibrozil but continued with tamoxifen therapy. Patient developed mild abdominal pain for 1 month but hesitated to visit the hospital until it progressed into severe epigastric pain with nausea and vomiting. Patient was managed in the intensive care unit for acute pancreatitis and hypertriglyceridemia with insulin drip. Tamoxifen was held during this time. Patient responded to the management well and discharged home with outpatient oncology follow up.

Discussion : Tamoxifen has been used in breast cancer treatment for many years, but long-term use can induce hypertriglyceridemia particularly in patients with pre-existing lipid disorder. It can have a paradoxical estrogenic effect on lipid metabolism resulting in elevated triglyceride and chylomicron levels. Increased blood levels of triglycerides cause lodging in pancreatic capillaries, resulting in pancreatitis. Close monitoring of lipid levels is crucial when patients are on tamoxifen therapy. It is of utmost importance to advise patients about possible life-threatening complications of tamoxifen induced hypertriglyceridemia. That may prevent missing a dose, changing the dose or stopping the lipid lowering medications without physicians’ directions. Collaborative efforts by endocrinologists, oncologists and primary care physicians play a key role in preventing similar conditions. Changing tamoxifen to an alternate treatment may be considered if the patient is noncompliant with lipid lowering medications.