The foot is composed of diverse tissues—skin, soft tissues, and bone—all of which are susceptible to malignant transformation. While cancer in the foot is relatively uncommon compared to other regions of the body, it can originate there as a primary tumor or spread from cancer elsewhere in the body. Understanding the possibility of foot cancer and its manifestations is important for prompt medical attention.
Primary Types of Cancer Affecting the Foot
Cancers in the foot are categorized by the specific tissue from which they arise: skin, soft tissue, or bone. Skin cancers are the most frequently encountered type of malignancy in the foot.
Skin Cancers
Malignant melanoma is the most concerning skin cancer, appearing on the soles, between the toes, or beneath a toenail. Although less common on the foot than in sun-exposed areas, melanoma here is serious and requires early detection. Squamous cell carcinoma is another common type, often presenting as a scaly patch, rough bump, or a non-healing open sore. Basal cell carcinoma can also occur on the foot, sometimes resembling a non-cancerous ulcer or pearly white bump.
Soft Tissue Cancers
Malignant tumors developing from soft tissues (fat, muscle, tendons, and blood vessels) are known as soft tissue sarcomas. Synovial sarcoma is one of the more frequently reported types in the foot and ankle, often affecting young adults. Other soft tissue malignancies like fibrosarcoma or liposarcoma are observed less often.
Bone Cancers
Primary bone cancers of the foot are exceedingly rare. Osteosarcoma, which originates in the hard part of the bone, and chondrosarcoma, which begins in cartilage, are two types that can occur. The bones of the midfoot, particularly the metatarsals, are sometimes the most common site for a bone tumor. These tumors can weaken the structure, potentially leading to a fracture without significant trauma.
Recognizing the Warning Signs
Patients should be aware of specific changes on or within their foot that indicate a potential issue warranting professional evaluation.
Skin Changes
A primary indication of a possible skin malignancy is the appearance of a new pigmented lesion or a change in an existing one. This includes alterations in the mole’s size, color, shape, or texture, often following the “ABCDE” characteristics of melanoma. Any sore, ulcer, or lesion on the foot that fails to heal after several weeks should be examined. Non-healing wounds that crack, bleed, or ooze fluid are concerning signs for skin cancer. Abnormal changes within the toenail, such as unexplained discoloration, dark streaks, or a change in nail shape, can also signal cancer growing beneath the nail bed.
Lumps and Pain
Unexplained lumps or masses, whether firm or soft, on the top or bottom of the foot should prompt a medical visit. These growths may be painless initially, potentially delaying the detection of soft tissue sarcomas. Persistent or worsening pain in the foot or ankle that is not clearly linked to an injury, and does not improve with rest or standard remedies, is another important symptom.
Medical Evaluation and Treatment Approaches
A medical evaluation for suspected foot cancer typically begins with a thorough physical examination, where the healthcare provider assesses the size, shape, and pigmentation of any suspicious lesions or masses. Following the initial assessment, imaging studies are generally ordered to better visualize the underlying structures of the foot. X-rays help identify bone involvement, while magnetic resonance imaging (MRI) provides detailed images of soft tissues, defining the tumor’s size and its relationship to surrounding structures.
Computed tomography (CT) scans may be used to assess the spread of cancer, particularly to the lungs, a common site for metastasis. A Positron Emission Tomography (PET) scan involves injecting a small amount of radioactive sugar, which cancer cells often absorb more readily than normal cells, helping to detect cancer throughout the body. However, the definitive diagnosis rests on a biopsy, where a small sample of the abnormal tissue is collected and examined under a microscope by a pathologist.
Treatment for foot cancer is highly individualized, depending on the cancer type, its stage, and its location. Surgery is the mainstay of treatment for most foot cancers and often involves removing the tumor along with a margin of healthy tissue. Surgeons aim for limb salvage, a procedure that removes the cancer while preserving as much of the foot’s function as possible.
Radiation therapy uses high-energy beams to destroy cancer cells. It may be employed before surgery to shrink a tumor or after surgery to eliminate any remaining cancer cells. Chemotherapy involves systemic anti-cancer drugs that travel through the bloodstream to kill cancer cells, and it is usually reserved for more aggressive or widespread cancers. Targeted therapies, which focus on specific molecular mechanisms within cancer cells, are also used for certain types of foot cancer.