MAX2—a convenient index to estimate the average per patient risk for chemotherapy toxicity

Cancer patients, especially the elderly, present with a highly variable susceptibility to toxicity from chemotherapy. To estimate correctly a patient's risk for toxicity, both the average toxicity of a chemotherapy regimen and patient-related variables need to be assessed. However, treatment toxicities are typically reported item by item, not summarised per patient. We tested an index derived from a pilot study, the MAX2, on the ECOG database. Studies including 20 or more patients aged 70 years and older per arm were selected. Four studies were identified, representing 2526 patients, 410 (16%) being elderly. The association of the MAX2 index with the per patient incidence of grade 4 haematological and/or grade 3 or 4 non-haematological toxicity was highly significant, both for the overall group and for the elderly subgroup. The MAX2 index is a convenient and reproducible way of comparing the average per patient risk for toxicity from chemotherapy across several regimens.