Tiredness happens to everyone -- it's a feeling you expect after certain activities or at the end of the day. Usually, you know why you are tired and a good night's sleep solves the problem.
Fatigue, which is often confused with tiredness, is a daily lack of energy, a whole-body tiredness not relieved by sleep. It can last for a short time (a month or less) or stay around longer (1-6 months or longer). Fatigue can prevent you from functioning normally and gets in the way of things you enjoy or need to do.
Cancer-related fatigue is one of the most common side effects of colorectal cancer and its treatment. It is not predictable by tumor type, treatment, or stage of illness. Usually, it comes on suddenly, does not result from activity or exertion, and is not relieved by rest or sleep. It is often described as "paralyzing" and may continue even after treatment is complete.
Chemotherapy. Any chemotherapy drug or regimen may cause fatigue. Fatigue usually develops after several weeks of chemotherapy. In some, fatigue lasts a few days, while others say the problem persists throughout the course of treatment and even after the treatment is complete.
Radiation therapy.Radiation, commonly used in the treatment of rectal cancer, can cause fatigue that increases over time. This can occur regardless of the treatment site. Fatigue usually lasts from 3 to 4 weeks after treatment stops, but can continue for up to 2 to 3 months.
Combination therapy. More than one cancer treatment at the same time or one after the other increases the chances of developing fatigue.