Raising hemoglobin: an opportunity for increasing survival?

Although the association between low hemoglobin levels and poorer outcomes in radiation oncology has long been recognized, anemia is often overlooked and untreated. However, a growing body of clinical evidence now indicates that low hemoglobin levels during radiation treatment are associated with decreased response and survival following radiotherapy. For example, a large Canadian retrospective study in patients receiving radical radiotherapy for cervical cancer showed that the 5-year survival rate was 19% higher in those whose hemoglobin during radiation treatment was =12 g/dl compared to those with levels <12 g/dl. The data suggest that clinical trials need to be performed to determine whether increasing hemoglobin levels leads to improved local control and survival. The mechanism by which low hemoglobin levels could cause poorer outcomes is not well understood and needs further elucidation. It is postulated that lower hemoglobin levels resulting in decreased oxygen carrying capacity may lead to increased tumor hypoxia, radiation resistance and increased tumor angiogenesis. The interrelationship of low hemoglobin levels, hypoxia, tumor angiogenesis and survival is explored in this article.