The presence of dark patches on the soles of the feet has a low correlation with bowel cancer, and it is quite rare for bowel cancer to metastasize to the soles of the feet with black, intact patches. However, bowel cancer may metastasize to the skin, bones, and skull. If a patient suspects that a black spot on the bottom of the foot is associated with tumor tissue, it is relatively simple to do a biopsy. A black spot on the bottom of the foot that is not stained or painful and has no other symptoms may be a melanoma. If it affects the patient’s quality of life with symptoms such as bumpiness, erosion or pain, promptly visit the hospital for a clear diagnosis and symptomatic treatment.