( from Cancermonthly.com)
Grades - Toxicities (or side-effects) are graded from one to five. The higher the number, the more toxic were the side-effects for the treatment. There are a number of different toxicity scales (i.e. National Cancer Institute Common Toxicity Criteria version 2.0, World Health Organization) and they are all similar in respect to their grades and definitions. The scale is generally:
1 = Mild side-effects
2 = Moderate side-effects
3 = Severe side-effects
4 = Life Threatening or Disabling side-effects
5 = Fatal
A few clinical reports describe toxicities, but fail to grade them. Others report no toxicities. In those cases, the toxicity grade is left blank.
Cancer Monthly Grade Number is the Highest Grade Experienced - For most therapies, patients will experience different toxicities with different grades. For example, for one particular treatment, the side effect of nausea may be graded as 2, while the side-effect of neutropenia may be graded as a 4. The grade numbers reported in the Search Results (1-5) represent the highest grade for one or more toxicities reported for one or more patients. This means that even if only one patient had one example of a grade 4 toxicity and every other patient had grade 2, the grade for that treatment will be reported as a 4.