Comparison of the Effectiveness of 8-week vs 12-week Physical Exercise Programmes in Patients With Colorectal Cancer

1. Introduction Colon cancer is one of the leading causes of morbidity and mortality worldwide, with an increasing incidence in many developed countries. In Spain, it is one of the most common types of cancer, accounting for approximately 15% of all cancer cases diagnosed, with an incidence of around 41,000 new cases annually. The mortality associated with colon cancer is significant, although there have been notable improvements in five-year survival rates, which currently stand at around 65%, thanks to advances in treatments and early diagnosis. Early diagnosis is crucial and has been facilitated by screening programs such as colonoscopy and fecal occult blood tests, which allow the detection of precancerous lesions and early-stage cancer. Treatments for colon cancer include surgery, radiotherapy, immunotherapy, and notably, chemotherapy. Chemotherapy is especially relevant in adjuvant treatment to reduce the risk of postoperative recurrence and in metastatic disease to control tumor growth and prolong survival. Modern chemotherapeutic agents, combined with targeted and supportive therapies, have significantly improved treatment outcomes, providing patients with better recovery prospects and an enhanced quality of life during and after treatment.

Chemotherapy is a crucial treatment in the fight against colon cancer, but unfortunately, its impact is not limited solely to cancer cells. Chemotherapeutic agents, designed to target rapidly growing cells, also affect healthy tissues, leading to various side effects. One of the most common adverse effects is peripheral neuropathy, a condition that affects the peripheral nerves and can manifest as sensations of tingling, numbness, pain, or weakness in the limbs. Chemotherapy-induced peripheral neuropathy can be especially challenging for patients with colon cancer, as it further worsens the quality of life during an already difficult period. The nerves responsible for motor and sensory function are compromised, affecting the patient's ability to perform daily activities and weakening their physical endurance.

This phenomenon adds to the emotional and physical burden of battling cancer. However, there are tools that can positively influence these adverse effects, such as physical exercise. Although it may seem contradictory, regular physical exercise has been shown to have beneficial effects on peripheral neuropathy. Physical exercise can improve blood circulation and promote the regeneration of damaged peripheral nerves.

Additionally, exercise helps alleviate the pain and discomfort associated with neuropathy, thereby strengthening patients' functional capacity.

Scientific research has demonstrated that physical exercise has multiple benefits for cancer patients, beyond alleviating peripheral neuropathy. Various studies have indicated that regular physical activity can significantly improve immune function, which is crucial for patients undergoing treatments that weaken the immune system. Exercise helps increase the production and efficiency of immune cells, enhancing the body's ability to fight infections and potentially inhibiting the growth of cancer cells.