Chemo cream refers to topical medications applied directly to the skin to treat specific dermatological conditions. These creams contain active ingredients that target abnormal or precancerous cells on the skin’s surface. As a localized treatment, their effects are primarily confined to the application area, with minimal absorption into the body. This approach addresses skin concerns without the systemic side effects often associated with traditional intravenous chemotherapy.
How Chemo Cream Works
Chemo creams primarily utilize two main active ingredients: 5-fluorouracil (5-FU) and imiquimod, each working through distinct mechanisms. 5-FU, a type of antimetabolite, operates by interfering with the synthesis of DNA and RNA within abnormal cells. It acts as a pyrimidine analog, binding to an enzyme called thymidylate synthetase, which is necessary for DNA replication. This inhibition prevents the abnormal cells from proliferating, ultimately leading to their death.
The application of 5-FU cream causes a sequence of skin reactions, including redness, blistering, shedding, and erosion, followed by re-epithelialization as healthy skin regrows. This visible reaction indicates the destruction of the targeted cells. 5-FU’s ability to selectively affect sun-damaged and precancerous cells, while largely sparing normal skin, makes it an effective topical treatment.
Imiquimod, on the other hand, functions as an immune response modifier. It stimulates the body’s own immune system to identify and destroy abnormal cells. Specifically, imiquimod activates Toll-like receptors 7 and 8 (TLR7 and TLR8) on immune cells like macrophages, monocytes, and dendritic cells. This activation triggers the release of various pro-inflammatory cytokines, such as interferon-alpha (IFN-α), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α). These cytokines then promote an immune response that leads to the death of diseased tissue and the clearance of abnormal cells.
Conditions Treated
Chemo creams are commonly prescribed for several specific skin conditions, particularly those that are superficial or precancerous. One frequent use is for actinic keratosis, which are rough, scaly patches resulting from chronic sun exposure. These lesions are considered precancerous, as they have the potential to develop into squamous cell carcinoma. Chemo creams effectively target and eliminate these sun-damaged cells, reducing the risk of progression.
Chemo creams are also used to treat superficial basal cell carcinoma (sBCC), a common type of skin cancer affecting the top layers of the skin. This treatment is considered for low-risk tumors, such as those smaller than 2 centimeters on the trunk or extremities. Another condition treated is squamous cell carcinoma in situ, also known as Bowen’s disease, an early, non-invasive form of squamous cell carcinoma.
Using Chemo Cream and Managing Side Effects
Applying chemo cream requires careful attention to instructions from a healthcare professional. The affected skin area should be washed and gently patted dry before application. A thin layer of cream is applied using a non-metal applicator, a gloved fingertip, or a clean fingertip, followed by thorough hand washing if bare fingers were used.
Frequency and duration vary by cream and condition, but range from once or twice daily for 2 to 6 weeks. For imiquimod, treatments are applied at night and left on for 6 to 10 hours before washing off with mild soap and water. Avoid applying the cream to the eyes, nose, mouth, or in skin folds where irritation may be more severe. Treated areas can be left uncovered or covered with a light gauze dressing, but airtight bandages are not recommended.
Patients should anticipate common side effects, as these indicate the cream is working effectively to destroy abnormal cells. These reactions can include redness, soreness, tenderness, itching, burning, and stinging in the treated area. The skin may also blister, peel, scab, or crust. These localized skin reactions are most intense during the second to third week of treatment and should gradually subside within a few weeks after stopping the cream.
To manage discomfort, a bland moisturizer can be applied to the treated area after the cream has been on for several hours, or in the weeks following treatment. Avoiding direct sunlight and using high SPF sunscreen (at least SPF 30) along with protective clothing is important, as chemo creams can increase sun sensitivity. Some individuals using imiquimod may experience flu-like symptoms such as fever, body aches, headaches, or swollen lymph nodes. If side effects become severe, interfere with daily activities, or if signs of infection like pus or excessive drainage appear, it is important to contact a healthcare professional for guidance.