Chemotherapy in malignant mesothelioma is targeted towards patients who are not good candidates for surgery. Chemotherapy is mainly employed to inhibit the growth or spread of the cancer. Its uses vary in different situations, and it may be used in a neoadjuvant, adjuvant or palliative manner in relation to the timing of surgery or any other treatments.
Neoadjuvant chemotherapy refers to the use of chemotherapy prior to the use of other treatments, usually surgery. This strategy is employed to aid in the shrinking of the size of the tumor, so the rates of success of any succeeding treatments done will be higher. Chemotherapy can also be used after surgery. If employed in this manner, this is referred to as adjuvant chemotherapy. This is usually aimed at eliminating any microscopic residual disease. Finally, if chemotherapy is used to relieve particular symptoms in the patient, this is termed as palliative chemotherapy. This is reserved for patient with the more advanced stages of malignant mesothelioma.
The chemotherapeutic drug combination that has been approved by the U.S. Food and Drug Administration (FDA) is Alimta (pemetrexed) with Cisplatin. This combination is the first chemotherapeutic regimen specific to malignant pleural mesothelioma that has been approved by the FDA, and is currently the first line of treatment for such. This combination has been shown to extend the median survival time of patients by 3 months as compared to treatment regimens using Cisplatin alone.
Prior to the start of treatment with the Alimta/Cisplatin combination, patients are required to start supplementation with Vitamin B12 and Folate. Vitamin B12 are to be given intramuscularly one week prior to treatment and repeated every 9 weeks during the duration of the treatment. Folate is to be taken orally daily starting at the same time as the Vitamin B12 injections and continued until 21 days after the last cycle of Alimta. An oral steroid medication is also given to minimize the associated skin rash.
The schedule of treatment cycle with the Alimta/Cisplatin combination is every 21 days. Treatment consists of a 10-minute IV infusion of Alimta followed by a 2-hour infusion of Cisplatin. The number of cycles administered is dependent on each patient’s response and adverse effects profile. Typically, 3 to 4 cycles are given before the patient is evaluated for a response to treatment. If after evaluation, a satisfactory response to treatment is gleaned, a set of criteria is used to decide whether or not chemotherapy should be resumed. This criteria include looking for evidence of tumor shrinkage, stability of the disease, or its continued progression. If the tumors have shrunk or the disease was kept stable by the treatment, then chemotherapy may be continued for as long as the patient can tolerate. If a progression of the disease was the response to treatment, then the chemotherapy should be terminated. Management of the patient should now be geared towards other options, that is, the possibility of palliative or hospice care.
Side effects that are to be expected are the same with any chemotherapeutic drugs, and typically includes nausea, vomiting, fatigue, as well as immunosuppression and an increased susceptibility to common infectious agents.
A suitable chemotherapy schedule should be tailored for each individual patient. Important factors to consider in coming up with this schedule include the patient’s response and tolerance profile to the regimen. If determined that chemotherapy is ineffective for a particular patient, then other treatment options should be explored without hesitation.