Chemotherapy, or chemo, is a type of cancer treatment in which drugs are used to attack cancer cells. Traditionally, chemotherapy doses are administered every three or four weeks, but chemotherapy shrinks tumors and smaller tumors grow at a faster rate. Dose-dense chemotherapy is given more frequently than usual, in order to catch more of these rapidly dividing tumor cells. Chemotherapy drugs affect healthy cells as well as cancer cells, and at least a three-week break between treatments was thought to be necessary to avoid losing too many white blood cells, which fight infection. Dose-dense chemotherapy overcomes this problem by giving patients drugs to boost blood cell production.
A problem limiting the frequency of chemo doses is that the treatment leads to low levels of white blood cells. White blood cells are part of the immune system and are essential for protecting the body against infection. If white cell levels fall too low, patients become vulnerable to infection, with potentially fatal results. This difficulty has restricted the minimum period between chemotherapy treatments to three or four weeks, limiting the total amount of a drug which can be administered in a given time.
Dose-dense chemotherapy allows a larger overall amount of a drug to be given per unit of time, and this may make it more effective at treating some cancers. Growth factors, which increase white blood cell production, are given alongside dose-dense chemotherapy. Other side effects can still occur and some patients in dose-dense chemo studies have experienced a decrease in red blood cells. There have also been reports of bone pain that may be associated with the use of growth factors.
Not all types of cancer respond to treatment with dose-dense chemotherapy. It seems to be beneficial for patients who have a type of breast cancer referred to as hormone receptor-negative. Around 25 percent of all cases of breast cancer are found to be hormone receptor-negative. There does not seem to be any clear benefit in using dose-dense chemotherapy for patients with hormone-receptor positive breast cancer.
Future research could help determine whether the dose-dense regime should be used for all breast cancer patients or if it would be more appropriate reserved for certain groups. Studies investigating the use of dose-dense chemotherapy for other cancers, such as lymphomas and ovarian tumors, have also shown mixed results. It is possible that certain patients could benefit, and ongoing studies may help identify which ones.