Dose-dense chemotherapy is a regimen that applies an accelerated chemotherapy schedule. It is a relatively new approach that has shown great potential, particularly in the treatment of estrogen-receptor-negative breast cancer.
Dose-Dense chemotherapy vs. Conventional Chemotherapy
Conventional chemotherapy is applied on a schedule of three week intersvals between treatments. This schedule was developed in order to give patients’ immune systems ample time to recover from damaged white blood cell counts brought about as a side effect of the chemotherapy. Dose-dense chemotherapy shortens the treatment cycle to two week intervals while maintaining roughly the same chemotherapy dosage as conventional chemotherapy.
Two major toxicities of chemotherapy are anemia, a deficiency of red blood cells and/or hemoglobin and neutropenia, a blood disorder characterized by an abnormally low number of neutrophil granulocytes, a type of white cell responsible for fighting infection. Because of heightened patient susceptibility to these disorders during dose-dense chemotherapy, the treatment is accompanied by a combination of drugs that boost red and white blood cell recovery. One study has found that this approach actually lowers the incidence of neutropenia in patients as compared to conventional chemotherapy.
The Theory of Dose-Dense chemotherapy
Dose-dense chemotherapy was developed on the theory of cancer cell growth and replication developed in the 1980’s known as the Gompertzian growth curve. Because chemotherapy is most effective when cancer cells are dividing the most rapidly, researchers speculated that timing chemotherapy dosage to attack cancer cells at their earliest stage of growth would yield superior results.
Dose-Dense Chemotherapy Clinical Trials
Clinical studies have shown mixed results in the effectiveness of dose-dense chemotherapy. The most success has been found in the treatment of breast cancer.
A clinical trial presented at the 2002 Annual San Antonio Breast Cancer Symposium found that women with breast cancer that had spread to the lymph nodes had an 82% disease-free survival rate compared to a rate of 75% for patients who had received conventional chemotherapy with no difference in the severity of side effects. The study, however, showed a significant benefit only in women with estrogen-receptor-negative disease, a condition which makes up only about 25% of breast cancer cases.
A Phase III trial conducted in Germany reported success with dose-dense chemotherapy in the treatment of lymphoma with survival rates of 70% compared to 62% for those treated with conventional chemotherapy. The study found a decreased quality of life for those treated with dose-dense chemotherapy, with recovery occurring within a few months of the treatment.
Dose-dense chemotherapy is also utilized in treating non-Hodgkin’s lymphoma; however, one of the largest studies to date showed improved survival rates only for those aged 61-75 years of age. Other studies have shown improvement across all age ranges.
Dose-dense chemotherapy has not been found successful in all cancer treatments. A recent study of bone cancer treatment found no significant difference in patient survival rates of those receiving dose-dense chemotherapy compared to those receiving conventional therapy.
Clinical trials are underway studying dose-dense chemotherapy of ovarian and lung cancer.