A new retrospective study has reported that neutropenia caused by chemotherapy for early breast cancer is associated with favorable five-year disease-free survival. Neutropenia is characterized by an abnormally low number of neutrophils, a type of white blood cell involved in infection fighting. The study included 103 early stage breast cancer patients who were treated with epirubicin-based chemotherapy followed by docetaxel (Taxotere). The association between neutropenia resulting from epirubicin-based chemotherapy and five-year distant disease-free survival was evaluated.
Thirty-one (30%) of the patients in the study developed neutropenia during the epirubicin-based regimen. Patients without neutropenia were found to have a significantly lower five-year distant disease-free survival rate (64%) than those with neutropenia (97%). Further analysis demonstrated that neutropenia is an independent prognostic factor for distant disease-free survival. The authors conclude that neutropenia occurring in early breast cancer patients during initial neoadjuvant treatment is strongly associated with a better prognosis.
Comments regarding the study
While severe chemotherapy-related neutropenia can be a significant problem, not the least because it can delay and prolong cancer treatment, moderate neutropenia has been found to be associated with more favorable outcomes in a variety of cancers, including gastric cancer, non-small cell lung cancer, and cervical cancer, in addition to breast cancer. However, a clear and convincing explanation for these findings has not been forthcoming.
It has also been suggested that the absence of chemotherapy-induced neutropenia can be interpreted as a result of chemotherapy-underdosing. On the other hand, some women actually experience an increase in white blood cell count (leukocytosis) during chemotherapy and it is doubtful that increasing the chemotherapy dose would induce neutropenia among these patients. Neutropenia may simply be a marker of susceptibility to chemotherapy that extends to both breast cancer cells and neutrophils among affected individuals. This suggests that, for some patients who do not experience chemotherapy-induced neutropenia, their disease may be characterized by base-line tumor-related leukocytosis and other tumor-specific factors that serve to prevent chemotherapy-induced neutropenia.