The grades provided in tables show the severity of the side effects as opposed to the grade of the lymphoma. Side effects are graded about as follows (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
Generally the reports group the higher grades separately because those are the ones that really matter (hurt the patient, require changing treatment regimen, require medical intervention).