Dacarbazine, commonly known as DTIC, is a chemotherapy medication used in the treatment of various cancers. It belongs to a class of drugs called alkylating agents, which work by interfering with the genetic material of cancer cells. DTIC is administered intravenously and aims to slow or stop the growth of cancer cells within the body. It is a standard part of certain cancer treatment regimens.
How DTIC Works
DTIC functions as an alkylating agent, by adding alkyl groups to cancer cell DNA. This process occurs after DTIC undergoes metabolic activation in the liver by certain liver enzymes. The activated form, methyl diazonium ion, then reacts with DNA. These reactions create DNA adducts, which are lesions that distort the DNA double helix.
The presence of these DNA adducts disrupts the normal processes of DNA replication and transcription. When the DNA damage is extensive and cannot be repaired, it triggers cell cycle arrest and ultimately leads to apoptosis, or programmed cell death, in the cancerous cells. DTIC is considered a “cell cycle non-specific” drug, allowing it to affect cancer cells at any stage of their growth cycle.
Cancers Treated with DTIC
DTIC chemotherapy is an established treatment for several types of cancer. It is widely used for metastatic malignant melanoma, a serious form of skin cancer that has spread to other parts of the body. For melanoma, DTIC can be administered as a single agent.
DTIC is also used to treat Hodgkin lymphoma, a cancer affecting the lymphatic system. In this context, it is often part of combination chemotherapy regimens, such as ABVD (Doxorubicin, Bleomycin, Vinblastine, and Dacarbazine). The medication may also be used for soft tissue sarcomas and has been explored for other neuroendocrine tumors or thyroid cancer, depending on the specific characteristics and stage of the disease.
Administration and Potential Side Effects
DTIC is administered intravenously (IV) directly into a vein. It can be given as a slow injection over several minutes or as a drip over a longer period, often ranging from 15 to 60 minutes. The frequency of treatment cycles varies depending on the cancer type and specific protocol, but it is commonly given every 3 to 4 weeks. Some patients may receive treatment through a central line, PICC line, or portacath, which are long plastic tubes inserted into a large vein for easier and safer administration over time.
Like other chemotherapy drugs, DTIC can affect healthy cells, leading to side effects. Common side effects include gastrointestinal issues such as nausea, vomiting, and loss of appetite, which can be severe and may last for several hours after treatment. Medications are often given beforehand to help manage nausea and vomiting. Fatigue and flu-like symptoms, including fever, body aches, and headaches, are also frequently reported and can occur during or a few days after treatment.
DTIC can cause myelosuppression, a decrease in bone marrow activity leading to low blood counts. This can result in a reduced number of white blood cells (leukopenia or neutropenia), increasing the risk of infection. A low platelet count (thrombocytopenia) can increase the risk of bruising or bleeding, while a low red blood cell count (anemia) can lead to breathlessness and paleness. Hair loss, or alopecia, is a common side effect, affecting scalp and body hair, though hair usually regrows after treatment ends.
More serious, but less common, side effects include liver toxicity, which can manifest as elevated liver enzyme levels or, rarely, severe liver failure. Allergic reactions are also possible, with symptoms such as shortness of breath, chest pain, rash, flushing, or a drop in blood pressure. Rarely, nerve damage, or changes in eyesight and confusion, have been reported. Tissue damage can occur if the medication leaks out of the vein at the injection site, causing redness, swelling, or pain.
Important Considerations During Treatment
Before beginning DTIC treatment, healthcare providers conduct blood tests to assess blood cell counts and liver and kidney function. Patients should discuss their medical history, including any infections or existing liver or kidney conditions, with their healthcare team. Anti-nausea medications are often prescribed to help manage potential gastrointestinal side effects.
Throughout the treatment course, regular blood tests are performed to monitor blood counts and liver function, allowing the healthcare team to adjust treatment as needed and manage side effects promptly. Patients are advised to practice good hand hygiene and avoid large crowds or individuals who are sick to reduce the risk of infection, especially due to potential low white blood cell counts. It is also important to maintain adequate nutrition and hydration to support the body during therapy.
Patients should avoid certain over-the-counter medications, such as aspirin or NSAIDs, without consulting their doctor, as these can increase the risk of bleeding due to low platelet counts. Sun sensitivity is a known side effect, so wearing sunscreen and protective clothing is advisable. Any new or worsening symptoms, such as fever (a temperature above 37.5°C or below 36°C), severe pain, unusual bleeding or bruising, or signs of an allergic reaction like difficulty breathing or rash, should be reported to the healthcare team immediately.