Chemotherapy cream is a localized medical treatment applied directly to the skin to address certain abnormal cell growths. Unlike systemic chemotherapy, which circulates throughout the body, this topical approach provides a focused therapeutic option. By concentrating the drug on the affected surface area, it targets precancerous and superficial cancerous cells while minimizing absorption into the rest of the body. This method is used for managing skin conditions arising from chronic sun exposure.
What Conditions Does It Treat
Topical chemotherapy treats conditions affecting the skin’s uppermost layers, making it effective for field treatment. The most common indication is Actinic Keratosis (AK)—rough, scaly patches representing early sun damage that can progress into skin cancer. Applying the cream over a broad area, known as field cancerization, helps eliminate both visible lesions and those that have not yet fully surfaced.
The cream is also frequently prescribed for certain forms of non-melanoma skin cancer, specifically superficial Basal Cell Carcinoma (sBCC). It also treats Bowen’s disease (SCC in situ), a non-invasive form of Squamous Cell Carcinoma. The treatment is typically reserved for non-aggressive, shallow lesions where the cancer has not penetrated beyond the epidermis.
How the Cream Works on Skin Cells
The mechanism of action centers on the active ingredient, typically fluorouracil, which functions as an antimetabolite. Fluorouracil is structurally similar to pyrimidines, the natural building blocks of DNA and RNA. Once absorbed into the skin cells, the fluorouracil is converted into active metabolites.
These metabolites interfere with the enzyme thymidylate synthetase, necessary for producing deoxythymidine monophosphate (dTMP). Since dTMP is essential for DNA synthesis and repair, its depletion disrupts the replication process of the cell’s genetic code. The drug preferentially targets abnormal, rapidly dividing cells, such as precancerous or cancerous cells, because they are more metabolically active and incorporate the drug more readily than healthy skin cells. This interference with genetic material ultimately leads to the programmed death of the abnormal cells, selectively clearing the damaged tissue.
Understanding the Treatment Cycle and Reactions
Chemo cream must be applied exactly as instructed by a healthcare provider, typically a thin layer once or twice daily. Duration for actinic keratosis ranges from two to four weeks, while superficial skin cancers may require a longer course. Patients should use a non-metal applicator or glove, washing hands immediately afterward to avoid spreading the drug.
A significant part of the treatment is the inflammatory reaction that develops on the treated skin. This response is not an allergic reaction but a sign that the cream is successfully identifying and destroying the abnormal cells. The reaction begins with erythema (redness), progressing to intense inflammation, often including vesiculation and desquamation (blistering and peeling).
As the treatment continues, the area may become sore, tender, and develop erosions or crusting, indicating the destruction of the defective skin cells. The severity of this localized reaction often correlates directly with the amount of underlying sun damage present, with areas of greater abnormality reacting more intensely. If the inflammation becomes too severe, the physician may advise temporarily stopping the application or adjusting the frequency.
The discomfort and visible damage are expected steps toward healing and are not a reason to prematurely discontinue the treatment. Patients must practice strict sun protection during the entire treatment period, as the cream increases sensitivity to ultraviolet radiation. Once the application phase is complete, the skin enters a healing phase that can last for one to two months.
During this post-treatment period, raw areas begin to re-epithelialize, forming new, healthy skin. To manage the residual soreness and discomfort, a healthcare professional may recommend bland emollients or a topical steroid cream. The goal is to allow the treated area to fully repair, which results in smoother skin and the elimination of the sun-damaged cells that were present.