Prognosis is the prior knowledge of outcome of a disease. To be able to determine how a disease is likely to behave, with or without treatment, it is necessary to know certain facts about the disease. These are called prognostic factors.
For cancers like lymphoma, many factors determine outcome. Some are directly related to the disease - the disease stage, how large the disease is, or which organs are involved.
Other factors depend on the person involved - the age or sex of the individual, or his or her capacity to tolerate intensive treatment.
Outcomes are also dependant on the exact type of treatment received. Different treatments don't lead to the same results.
Factors that predict for a better outcome are called 'good' or 'favorable' prognostic factors. Those that predict for worse outcomes are called 'poor' prognostic factors.
