Major Findings

Capecitabine is a chemotherapy drug used to treat various types of cancer, including breast cancer and colorectal cancer. It has shown to be effective in inhibiting cancer cell growth. However, several studies have demonstrated that capecitabine can cause side effects, such as those reported in 9 and 14 .

The study in 6 suggests that consuming milk and eggs may increase the risk of side effects from capecitabine. These foods may affect the metabolism of capecitabine, resulting in an increased risk of side effects.

Capecitabine can be used to prevent chemotherapy-induced peripheral neuropathy caused by chemotherapeutic agents such as oxaliplatin and paclitaxel, as shown in 3 . Capecitabine has an effect of reducing damage to nerve cells and can suppress the risk of peripheral neuropathy.

The study in 19 reports a case where a patient with HER-2+ breast cancer undergoing peritoneal dialysis experienced grade II hand-foot syndrome and grade II diarrhea after taking a combination of pyrotinib and capecitabine. However, despite these side effects, the patient's tumor was significantly reduced. This case suggests that the combination of pyrotinib and capecitabine has potential therapeutic benefits in HER-2+ breast cancer patients with end-stage renal disease, but side effects should be monitored closely.

Reasons for Side Effects

Capecitabine's side effects are related to its metabolic pathway. Capecitabine is converted to its active metabolite, 5-fluorouracil, after several steps when it enters the body. 5-fluorouracil inhibits the growth of cancer cells by inhibiting DNA synthesis in cancer cells. However, 5-fluorouracil can also act on normal cells, causing a variety of side effects.

Common Side Effects

Gastrointestinal Side Effects

The most common side effects of capecitabine are gastrointestinal side effects, including nausea, vomiting, diarrhea, abdominal pain, and loss of appetite, as reported in 9 . These side effects can occur because 5-fluorouracil also acts on the cells of the digestive system. These symptoms are usually mild to moderate, but can become severe. If severe gastrointestinal side effects occur, capecitabine administration may need to be stopped or the dose reduced.

Skin Side Effects

Capecitabine can also cause hand-foot syndrome, as reported in 9 . Hand-foot syndrome is a condition where redness, swelling, pain, and numbness occur on the palms of the hands and soles of the feet. These symptoms often develop a few weeks after starting capecitabine and can be severe. If severe hand-foot syndrome occurs, capecitabine administration may need to be stopped or the dose reduced.

Neurological Side Effects

Capecitabine can also cause neuropathy, as shown in 18 . Neuropathy can cause symptoms such as numbness, pain, and paralysis in the hands and feet. These symptoms often develop a few weeks after starting capecitabine and can be severe. If severe neuropathy occurs, capecitabine administration may need to be stopped or the dose reduced.

Hematologic Disorders

Capecitabine can cause hematologic disorders, such as anemia, as shown in 9 . Anemia is caused by a decrease in the number of red blood cells in the blood and can cause symptoms such as fatigue, shortness of breath, and dizziness. If severe hematologic disorders occur, capecitabine administration may need to be stopped or the dose reduced.

Liver Disorders

Capecitabine can damage liver cells, potentially causing liver disorders. Liver disorders can cause symptoms such as jaundice (yellowing of the skin and whites of the eyes), fatigue, loss of appetite, and abdominal pain. If severe liver disorders occur, capecitabine administration may need to be stopped or the dose reduced.

Cardiac Disorders

Capecitabine can also cause cardiac disorders, as reported in 9 . Cardiac disorders can cause symptoms such as heart failure, atrial fibrillation, and ventricular tachycardia. If severe cardiac disorders occur, capecitabine administration may need to be stopped or the dose reduced.

Other

Capecitabine can cause other side effects, as shown in 9 . These side effects include fever, hair loss, taste changes, and weight loss. These symptoms are usually mild to moderate, but can become severe. If severe side effects occur, capecitabine administration may need to be stopped or the dose reduced.

Countermeasures for Side Effects

Countermeasures for Gastrointestinal Side Effects

Gastrointestinal side effects can be reduced through dietary therapy and drug therapy, as shown in 9 . Dietary therapy includes eating easily digestible foods, eating small meals frequently, and drinking plenty of fluids. Drug therapy includes antiemetics and antidiarrheals.

Countermeasures for Skin Side Effects

Hand-foot syndrome can be reduced through cryotherapy, as shown in 9 . Cryotherapy is a method of lowering the temperature of the hands and feet by using cooling pads or cooling sprays. To prevent hand-foot syndrome, it is effective to apply a moisturizer to the hands and feet and avoid rubbing them too much.

Countermeasures for Neurological Side Effects

Neuropathy can be reduced by taking supplements such as vitamin B complex, as shown in 18 . Vitamin B complex has an effect of promoting the repair of nerve cells. To prevent neuropathy, it is effective to cool the hands and feet and improve blood circulation in the hands and feet.

Countermeasures for Hematologic Disorders

Anemia can be improved by taking iron supplements or hematopoietic agents, as shown in 9 . Iron supplements increase the number of red blood cells in the blood. Hematopoietic agents promote hematopoietic function in the bone marrow.

Countermeasures for Liver Disorders

Liver disorders can be improved by taking liver protectants, as shown in 9 . Liver protectants have an effect of protecting liver cells. To prevent liver disorders, it is important to avoid putting a burden on the liver by limiting alcohol intake and avoiding fatty foods.

Countermeasures for Cardiac Disorders

Cardiac disorders require drug therapy to reduce the burden on the heart and lifestyle changes, as shown in 9 . Drug therapy to reduce the burden on the heart includes diuretics, vasodilators, and beta-blockers. Lifestyle changes include quitting smoking, reducing salt intake, and getting regular exercise.

Comparison Between Studies

Common Points of Studies

These studies show that capecitabine is an effective treatment for cancer but also indicate that there is a risk of side effects. Many studies have reported that capecitabine can cause side effects such as gastrointestinal side effects, skin side effects, neurological side effects, hematologic disorders, liver disorders, and cardiac disorders.

Differences in Studies

These studies show that the incidence and severity of capecitabine's side effects vary from patient to patient. In some studies, capecitabine's side effects were mild and did not require special treatment. However, other studies required stopping capecitabine administration or reducing the dose because the side effects were severe. The incidence and severity of capecitabine's side effects may vary depending on the patient's age, sex, type of cancer, treatment history, and concomitant medications. In addition, 6 differs from other studies in suggesting that milk and eggs may be risk factors for adverse effects of capecitabine-based chemotherapy in Chinese colorectal cancer patients.

Cautions for Application in Daily Life

Capecitabine is an effective drug for treating cancer, but it has the risk of side effects. It is important to take capecitabine as directed by your doctor. It is also important to be aware of changes in your health while taking capecitabine. Consult your doctor immediately if you notice any changes in your health.

Limitations of Current Research

Research on the side effects of capecitabine is still not sufficient. Further research is needed to gain a better understanding of the side effects of capecitabine. In particular, larger clinical trials are needed to understand how the incidence and severity of capecitabine's side effects vary depending on individual differences among patients.

Future Research Directions

Future research on the side effects of capecitabine needs to proceed in the following directions.

• Analyze the incidence and severity of capecitabine's side effects in detail by individual differences among patients.
• Develop methods to prevent capecitabine's side effects.
• Develop methods to reduce capecitabine's side effects.

Conclusion

Capecitabine is an effective drug for treating cancer, but it has the risk of side effects. It is important to take capecitabine as directed by your doctor and to be aware of changes in your health. Research on the side effects of capecitabine is still not sufficient. Further research on the side effects of capecitabine is expected to improve the safety and efficacy of capecitabine in the future.