Cancer can affect the foot either via a primary tumor in a tissue in the foot or as a secondary tumor from a more proximal metastasis.

Cancer can affect the foot in several ways, both directly and indirectly. Primary cancers of the foot are rare, but tumors can develop in the bones, soft tissues, or skin of the area. For example, malignant melanoma may arise on the skin of the foot, often mistaken at first for something less serious like a mole or wart. Bone cancers such as osteosarcoma or chondrosarcoma can also appear in the small bones of the foot, causing localized pain, swelling, and deformity. Because of the limited soft tissue around the bones in the foot, even small tumors may cause significant symptoms.

The impact of cancer on the foot can also come from metastasis. Cancers originating in other parts of the body, such as the lungs or breast, can spread to the bones of the foot, though this is uncommon. When it does occur, patients may experience persistent, unexplained pain that worsens at night or with weight-bearing activities. Metastatic lesions often weaken the bone structure, increasing the risk of pathological fractures in the foot, which can severely limit mobility and quality of life.

Treatment for foot cancers often involves a combination of surgery, radiation, and chemotherapy, depending on the type and stage of the tumor. Surgery might range from excision of small lesions to partial or full amputation of the affected area if the cancer is extensive. This can have profound consequences for walking, balance, and daily activities. Even when surgery is successful, rehabilitation and custom orthotic support are often necessary to restore function and reduce discomfort.

Beyond the direct effects of cancer, treatments themselves can also impact foot health. Chemotherapy and radiation may cause peripheral neuropathy, leading to numbness, tingling, or burning pain in the feet. These nerve changes can make walking difficult and increase the risk of injuries or ulcers, especially in patients with other conditions like diabetes. Additionally, reduced blood supply from radiation damage or surgical interventions can impair healing in the foot, making it especially vulnerable to infection and long-term complications.

Most Useful Resources:
Cancer (Foot Health Forum)
Cancer threads (Podiatry Arena)
Cancer metastasis in the foot (Podiatry Arena)
Cancer and the Foot (PodiaPaedia)
The Oncologist (Podiatry Apps)