Induction treatment, often simply referred to as induction, is the first therapy used to reduce the number of cancer cells. For myeloma, induction typically includes chemotherapy, which is followed by other treatments, such as irradiation or stem cell transplantation, to eliminate the cancer that remains. Induction treatment may also be called induction therapy, initial treatment, first-line therapy or primary treatment. Different classes of drugs are used for induction of myeloma, with most patients receiving a combination.
Considerations
According to the Multiple Myeloma Research Foundation, the type of induction chosen for patients with multiple myeloma depends on several factors, including the patient's age and general health, comorbidities and symptoms. The most important factor influencing the choice is whether the patient is a candidate for stem cell transplantation. Disease stage and laboratory test results also influence the decision, as does the types of complications.
Transplant Candidates
If the patient is a candidate for stem cell transplant, induction chemotherapy is likely to exclude melphalan, as this drug has a toxic effect on stem cells, reducing their numbers to the extent that collection is difficult. Stem cells are collected from the patient for transplant after three or four months of induction treatment. According to Blood, for many years standard induction was a combination of two chemotherapy drugs, vincristine or doxirubicin, with the steroid dexamethasone. Common induction regimens used today, however, are dexamethasone combined with an immunomodulating agent such as thalidomide or lenalidomide, or with bortezomib, a novel drug that causes cancer cells to die by blocking the action of proteasomes. Following removal of stem cells, the patient receives high-dose chemotherapy that destroys almost all the cells in the bone marrow, after which the frozen stem cells are transfused back into the bone marrow.
Patients Who Are Not Eligible for Transplant
Myeloma patients who are not candidates for transplantation, typically because they are too old or frail to survive the procedure, receive a standard induction regimen. According to the Mayo Clinic, the most common regimens are MPT: a combination of melphalan, a chemotherapeutic agent, with prednisone, a steroid and thalidomide or MPV: the first two drugs combined with bortezomib, a proteosome inhibitor. If side effects are severe, thalidomide may be removed from MPT or low-dose dexamethasone may be used with lenalidomide, a thalidomide analog that is more tolerable. Patients who are not eligible for transplant receive induction for 12 to 18 months, in cycles, with a rest period between each treatment.
High-Risk Myeloma
According to Blood, incorporating novel agents into induction treatment is emerging as an excellent strategy for patients with high-risk myeloma, whose survival rate with standard therapy, including transplant, has averaged only 2 years. According to the American Society of Hematology, the introduction of novel agents within the past decade has led to a 50-percent improvement in survival in newly diagnosed multiple myeloma.
Side Effects
The side effects of induction therapy depend on the dose and choice of drug and what combinations are used, reports the National Cancer Institute. Common side effects are reduced blood cell counts, which increase the chance for infection, bruises, easy bleeding and fatigue. Standard chemotherapy agents cause hair loss, while chemotherapy and targeted agents cause gastrointestinal effects such as upset stomach, loss of appetite and mouth sores. Diarrhea and constipation may occur as well.
References
- Blood; Multiple Myeloma; Kyle RA, Rajkumar V.; 2008
- National Cancer Institute: What You Need to Know About Multiple Myeloma
- Mayo Clinic: Multiple Myeloma
- Multiple Myeloma Research Foundation: Trends in the Treatment of Multiple Myeloma
- American Society of Hematology: Recent Increase in Multiple Myeloma Survival; 2007
