Does chemotherapy-induced neutropenia improve survival in metastatic colorectal cancer?

This study investigated whether chemotherapy-induced neutropenia improves survival of patients with metastatic colorectal cancer.

Metastatic colorectal cancer is colorectal cancer that has spread to other parts of the body. For unresectable (cannot be surgically removed) metastatic colorectal cancer, chemotherapy is the only option. Chemotherapy may lead to reduction of various blood components (hematological toxicity), which can cause neutropenia (defined as an abnormally low count of neutrophils, a type of white blood cell). Although neutrophils help protect the body against infection, they are associated with growth of cancer cells. Neutrophils do this by promoting inflammation and the development of new blood vessels that supply nutrients to the cancer cells.

 Preventing the increase of neutrophil levels is thought to be an effective way of preventing spread of cancer. This study investigates whether chemotherapy-induced neutropenia (lowering the level of neutrophils using drugs that are toxic to living cells) improves survival in metastatic colorectal cancer..

The study involved 399 patients with metastatic colorectal cancer. 88% of patients received more than two lines of chemotherapy i.e. additional chemotherapy drugs used when the initial drug(s) fail. The drugs used were 5-flurouracil, oxilaplatin (Eloxatin)and irinotecan (Campto).  72% of patients received targeted therapy (drugs that block the growth and spread of cancer by interfering with the specific molecules involved) including anti-EGFR (Tarceva) and/or bevacizumab (Avastin). By the end of the study, 77.9% of patients had died.

 The FOLFOX group (204 patients) received a FOLFOX regimen (5-flurouracil plus oxaliplatin) alone or with targeted therapies. The FOLFIRI group (113 patients) received a FOLFIRI regimen (5-flurouracil plus irinotecan) alone or with targeted therapies. The mono-therapy group (82 patients) received mono-therapy (treatment with one type of drug) involving a fluoropyrimidine  (e.g. 5-fluroruacil) or a targeted therapy. Follow-up was an average of 6.3 years.

For all treatment groups, patients with at least one episode of neutropenia had significantly better overall survival than the patients without. In the FOLFOX group, patients with neutropenia had an average overall survival of 47months while those without had an overall survival of 27months. In the FOLFIRI group, patients with neutropenia had an average overall survival of 41months while those without had an overall survival of 25months. In the mono-therapy group, patients with neutropenia had an average overall survival of 34months while those without neutropenia had an overall survival of 22months.

In summary neutropenia during chemotherapy for metastatic colorectal cancer was associated with increased survival.

Use of different chemotherapy regimens may have influenced survival outcomes, independent of the presence of neutropenia.