Major Research Findings

Cabozantinib has demonstrated effectiveness in treating advanced thyroid cancer. 14 reported that cabozantinib showed significantly higher response rates in patients with advanced and progressive medullary thyroid cancer compared to placebo, with a 28% versus 0% response rate. Additionally, progression-free survival was significantly longer in the cabozantinib group (11.2 months) compared to the placebo group (4.0 months). 6 highlights that cabozantinib is used to treat both differentiated and medullary thyroid cancer. However, it also emphasizes the non-negligible toxicity associated with this drug. Dose adjustments or treatment interruptions are common, and in rare cases, permanent discontinuation and even fatal side effects have been reported. 5 lists side effects of cabozantinib, including diarrhea, hypertension, fatigue, and hand-foot syndrome. 3 details a series of seven medullary thyroid cancer patients who discontinued cabozantinib treatment due to concerns about long-term toxicity or side effects. The possibility of tumor progression after cabozantinib discontinuation underscores the importance of carefully weighing the benefits and risks before and during treatment with this drug.

Reasons for Side Effects

Cabozantinib is a multi-kinase inhibitor that targets a variety of tyrosine kinase receptors, including MET, VEGFR2, and RET. 14 The side effects of cabozantinib are thought to be caused by its inhibitory effects on these receptors. For instance, inhibiting VEGFR2 can suppress angiogenesis, potentially causing side effects such as hand-foot syndrome and hypertension. Similarly, inhibiting MET might contribute to side effects like diarrhea and nausea. 1 The combination of these inhibitory effects on multiple targets likely contributes to the diverse range of side effects observed with cabozantinib.

Common Side Effects

Diarrhea

Diarrhea is one of the most frequently reported side effects of cabozantinib. 14 5 12 It's believed to occur as a result of cabozantinib's effects on intestinal cells.

Hypertension

Cabozantinib has the potential to induce hypertension. 5 12 The mechanism might involve cabozantinib's inhibition of angiogenesis.

Fatigue

Fatigue is another possible side effect of cabozantinib. 14 5 It may occur due to cabozantinib's influence on the body's energy metabolism.

Hand-Foot Syndrome

Hand-foot syndrome is a side effect that can be associated with cabozantinib. 14 5 12 This syndrome is likely caused by cabozantinib's inhibition of angiogenesis.

Countermeasures for Side Effects

Diarrhea

Staying hydrated and taking antidiarrheal medication are important steps for managing diarrhea. 6 12 If diarrhea is severe or persists, consulting with your doctor is recommended.

Hypertension

Antihypertensive medications can be prescribed to manage hypertension. 6 12 Regular blood pressure monitoring and discussion with your doctor are essential if you have concerns about hypertension.

Fatigue

Getting sufficient rest and sleep is crucial for managing fatigue. 6 12 If fatigue is severe or persistent, consulting with your doctor is important.

Hand-Foot Syndrome

Applying moisturizers and avoiding extreme cold temperatures can help manage hand-foot syndrome. 6 12 If hand-foot syndrome is severe, your doctor should be consulted.

Comparison between Studies

Commonalities among Studies

Numerous studies have shown cabozantinib's effectiveness in treating advanced thyroid cancer. 14 12 13 11 10 5 8 These studies consistently indicate that cabozantinib can cause side effects like diarrhea, hypertension, fatigue, and hand-foot syndrome.

Differences among Studies

The effectiveness and severity of cabozantinib's side effects can vary across different studies. For example, 14 reported a response rate of 28%, while other studies observed response rates around 10%. 17 The incidence and severity of side effects also differ between studies and are likely influenced by individual patient characteristics and dosage.

Points to Note Regarding Application to Real Life

Cabozantinib is a valuable treatment option for advanced thyroid cancer, but it's crucial to be aware of the potential side effects. Before starting treatment, patients should discuss the benefits and risks thoroughly with their doctors. Continued monitoring by a physician and regular checkups are essential throughout cabozantinib therapy. If you experience any concerning side effects, prompt consultation with your doctor is highly recommended.

Limitations of Current Research

Research on cabozantinib is still ongoing, and more data are needed, especially regarding its long-term safety and effectiveness. 3 The development of novel therapies to reduce cabozantinib's side effects is a promising area of future research.

Future Research Directions

Large-scale clinical trials are necessary to comprehensively evaluate the long-term safety and effectiveness of cabozantinib. 16 Developing new therapies that mitigate cabozantinib's side effects is another priority. Research focused on finding alternative treatments for patients who do not respond well to cabozantinib is also highly desirable.

Conclusion

Cabozantinib offers a valuable treatment option for advanced thyroid cancer, but it's essential to be aware of the potential side effects. Before considering cabozantinib therapy, it's crucial to have open and thorough discussions with your doctor to understand the benefits and risks. Continued research is expected to provide further insights into the safety and effectiveness of cabozantinib in the long term.