Cancer can have profound and multifaceted effects on the feet, influencing the skin, soft tissue, bones, and overall mobility. Although cancers of the foot are uncommon, they can be both primary—originating in the foot—or secondary, where cancer from another part of the body spreads to this region. The following essay explores the different types of cancers that can affect the feet, their symptoms, diagnostic challenges, the impact of cancer treatments on foot health, and the broader implications for patient quality of life.
Types of Cancer That Affect the Feet
Cancers that develop in the foot fall primarily into three categories: skin cancers, bone cancers, and soft-tissue cancers. Skin cancers are the most common, but each type presents unique challenges and risks.
Skin Cancers:
Among skin cancers, squamous cell carcinoma, basal cell carcinoma, and malignant melanoma are most frequently seen on the feet. Squamous cell carcinoma usually manifests as small rough patches or open sores that can appear deceptively benign. If untreated, it can invade deeper tissues or spread to other areas. Basal cell carcinoma is less aggressive and tends to remain localized, presenting as pearly or scaly patches most often on the tops of the feet. Melanoma, particularly acral lentiginous melanoma, is the most dangerous skin cancer affecting the foot because it can appear in places that are not exposed to sunlight, such as under the toenails or on the soles, making diagnosis difficult. Melanoma often masquerades as a mole or fungal infection and has a higher risk of metastasis.
Bone Cancers:
Bone cancers of the foot, though rare, can be particularly aggressive. The most prevalent types include osteosarcoma, Ewing’s sarcoma, and chondrosarcoma. These cancers often present as persistent, deep-seated pain that worsens at night, along with swelling or visible lumps. Studies have shown that bone cancer of the foot can affect any region—ranging from the toes and forefoot to the midfoot and hindfoot—with variable manifestations. For instance, osteosarcoma and chondrosarcoma are more likely to occur in the forefoot and toes, while Ewing’s sarcoma often arises in the hindfoot. The challenges of diagnosing these conditions lie in their resemblance to benign foot disorders or sports injuries.
Soft Tissue Sarcomas:
Soft-tissue sarcomas are cancers that develop in connective tissues, including muscles, fat, and blood vessels. Synovial sarcoma, for example, commonly appears around the foot and ankle. Because the foot contains limited soft tissue, these cancers often mimic benign growths and are overlooked until they grow significantly. Soft-tissue sarcomas can cause noticeable lumps, restricted mobility, and pain as they invade adjacent nerves and structures.
How Cancer Manifests in the Feet
Cancer presents uniquely in the feet due to the anatomy and physiological demands of this area. Symptoms may include persistent pain, visible or palpable lumps, non-healing sores, and discolored patches that may be mistaken for fungal infections, warts, or trauma. The subtle nature of these symptoms often leads to misdiagnosis or delayed intervention.
Bone cancers such as osteosarcoma weaken the structural integrity of foot bones, increasing the risk of fractures even under normal walking conditions. In soft-tissue tumours, patients may notice swelling or mass growth that affects their gait or ability to wear shoes comfortably. Similarly, melanoma may present as a dark streak under the toenail or a pigmented lesion on the sole, occasionally accompanied by bleeding or ulceration.
Secondary Cancers and Metastasis to the Feet
In some cases, cancers that begin elsewhere in the body metastasize to the feet. This phenomenon is primarily seen in advanced stages of cancer, where malignant cells spread through the circulatory or lymphatic system. Common primary sources include lung, breast, kidney, and prostate cancers that eventually lead to secondary tumors in the bones or soft tissues of the feet. These metastatic lesions often cause pain, swelling, and decreased mobility, complicating the patient’s overall prognosis.
Impact of Cancer Treatments on Foot Health
Beyond the effects of cancer itself, modern cancer treatments can profoundly impact the feet. Chemotherapy, radiation, and targeted therapies often produce dermatologic and neurological side effects collectively known as podiatric adverse events.
Chemotherapy-related Effects:
Chemotherapy can weaken nails, causing discoloration, brittleness, and separation from the nail bed. The treatment is also known to cause hand-foot syndrome, characterized by redness, swelling, pain, and sensitivity in the palms and soles. This condition can make walking painful, forcing some patients to reduce activity or modify treatment regimens.
Neuropathy and Circulatory Changes:
Many cancer medications cause peripheral neuropathy—damage to nerves responsible for sensation in the feet—which leads to tingling, numbness, or burning pain. Neuropathy not only diminishes quality of life but also increases the risk of injuries and infections, as patients might not feel minor wounds or pressure sores developing due to ill-fitting shoes. Radiation therapy may also damage blood vessels, impairing circulation and slowing the healing of wounds on the feet.
Secondary Infections and Dermatologic Changes:
Patients undergoing treatment often experience compromised immune systems, making them more susceptible to infections. Xerosis (dry skin), hyperkeratosis (thickened skin), and edema (swelling) are common secondary effects. These changes can exacerbate discomfort, limit movement, and increase susceptibility to cracks or sores, serving as potential entry points for pathogens.
Diagnostic Challenges in Foot Cancers
Diagnosing cancer in the foot is a significant challenge due to the foot’s complex anatomy and the overlap between cancer symptoms and benign conditions. Conditions such as plantar warts, fungal infections, and trauma-induced lesions can mimic early cancer symptoms. Moreover, the nonspecific nature of pain or lumps can delay imaging tests and biopsy procedures. For example, synovial sarcoma often grows slowly and painlessly, leading patients and clinicians to dismiss it as a benign cyst or fibroma.
For accurate diagnosis, specialists rely on imaging such as MRI or CT scans to determine the extent of soft tissue or bone involvement, followed by a biopsy for definitive pathological analysis. Patient education plays a crucial role in ensuring early medical attention for persistent foot abnormalities.
Psychological and Lifestyle Impact
Cancer affecting the feet not only disrupts physical function but also profoundly influences psychological well-being. The feet are crucial for mobility, independence, and quality of life; therefore, pain or structural damage from cancer or its treatment can impair the ability to walk, work, or engage in social activities. Swelling, ulceration, or surgical amputations necessary in some cases can lead to body image concerns and depression.
Cancer survivors often face long-term complications such as chronic pain or neuropathy, requiring continuous podiatric care and physiotherapy. Support from podiatrists, oncologists, and rehabilitation specialists is essential to restore mobility, manage pain, and prevent infections.
Cancer’s effect on the feet exemplifies the disease’s systemic and multifactorial nature. Whether through direct malignancies such as melanoma, synovial sarcoma, or osteosarcoma, or through indirect damage from chemotherapy and radiotherapy, the feet are not immune to the impact of cancer. Symptoms like non-healing sores, lumps, or persistent pain should never be ignored, as early detection greatly improves outcomes. Comprehensive care—encompassing prompt diagnosis, effective treatment, foot care management, and patient education—is crucial to maintaining mobility and preserving quality of life for those affected by cancer in the feet.