Carcinoma Medular de Tiroides and GLP-1 Receptor Agonist Therapy

Introduction and Special Considerations

The American Gastroenterological Association and American College of Gastroenterology note that personal history of medullary thyroid carcinoma (MTC) is relevant to the condition 1
The American Diabetes Association and American College of Obstetricians and Gynecologists recommend consideration of pregnancy or planning for pregnancy in patients with certain conditions 2

GLP-1 receptor agonist therapy is contraindicated in patients with active gastrointestinal malignancies, MTC, multiple endocrine neoplasia syndrome type 2 (MEN2), or any active or recent malignancy (within 5 years) 3, 1, 4
Patients with a personal or family history of MTC or MEN2 should not be treated with GLP-1 receptor agonists, including semaglutide 1, 4
Active gastrointestinal malignancies are a contraindication due to the potential for GLP-1 receptor agonists to enhance growth of colonic and gastrointestinal polyps and accelerate cancer growth 3

The American Gastroenterological Association recommends colonoscopy before initiating treatment in patients with risk factors for colorectal cancer, and periodic colonoscopy monitoring while on therapy 3
Patients should be screened for personal or family history of MTC or MEN2 before initiating therapy, with initial assessment including screening for contraindications and risk factors 5, 1, 4
Regular ophthalmologic examinations are recommended for patients with pre-existing diabetic retinopathy, as semaglutide may increase the risk of retinopathy complications 6

Gastrointestinal effects, including nausea, vomiting, diarrhea, constipation, and abdominal pain, are common adverse effects of GLP-1 receptor agonists, including semaglutide, and are dose-dependent 5, 1, 7
Risk of pancreatitis requires monitoring and stopping medication if severe abdominal pain occurs, with or without vomiting, and caution in patients with history of gallbladder disease due to increased risk 5, 4
Potential risk of acute kidney injury when initiating or increasing doses, and close monitoring essential for patients with severe renal impairment (eGFR <30 mL/min/1.73m²) 5, 4, 7
Maintain vigilance for changes in mood or suicidal thoughts, and consider baseline mental health assessment before initiating therapy, with regular monitoring of mental health 5, 4, 7

GLP-1 receptor agonists, such as semaglutide and liraglutide, can be safely used for obesity treatment in Asian patients, but require lower BMI thresholds for initiation and careful monitoring for specific adverse effects, as recommended by the American College of Cardiology and other guideline societies 5, 1, 4
The recommended BMI thresholds for GLP-1 agonist therapy in Asian patients are BMI >27 kg/m² without complications and BMI >25 kg/m² with obesity-related complications, or alternatively, waist circumference at least 10 cm greater than the upper limit of normal for Asian men and women, with careful consideration of contraindications and risk factors 5

Gradual dose titration every 4 weeks is essential to minimize side effects of GLP-1 receptor agonists, including semaglutide, with weekly dose titration by 0.6 mg as tolerated recommended for liraglutide 5, 7
Semaglutide has the highest efficacy for weight loss, with a 10.3-12.4% weight loss at 68 weeks, while liraglutide has moderate efficacy for weight loss, with a 5.6% weight loss at 1 year 5