Karnofsky was among the first to champion the evaluation of a chemotherapeutic agent's benefit by carefully quantitating its effect on tumor size and using these measurements to objectively decide the basis for further treatment of a particular patient or further clinical evaluation of a drug's potential. A partial response (PR) is defined conventionally as a decrease by at least 50% in a tumor's bidimensional area; a complete response (CR) connotes disappearance of all tumor; progression of disease signifies an increase in size of existing lesions by 25% from baseline or best response or development of new lesions; and "stable". | Chapter 081. Principles of Cancer Treatment Part 7 Karnofsky was among the first to champion the evaluation of a chemotherapeutic agent s benefit by carefully quantitating its effect on tumor size and using these measurements to objectively decide the basis for further treatment of a particular patient or further clinical evaluation of a drug s potential. A partial response PR is defined conventionally as a decrease by at least 50 in a tumor s bidimensional area a complete response CR connotes disappearance of all tumor progression of disease signifies an increase in size of existing lesions by 25 from baseline or best response or development of new lesions and stable disease fits into none of the above categories. Newer evaluation systems utilize unidimensional measurement but the intent is similar in rigorously defining evidence for the activity of the agent in assessing its value to the patient. If cure is not possible chemotherapy may be undertaken with the goal of palliating some aspect of the tumor s effect on the host. Common tumors that may be meaningfully addressed with palliative intent are listed in Table 81-1 E. Usually tumor-related symptoms may manifest as pain weight loss or some local symptom related to the tumor s effect on normal structures. Patients treated with palliative intent should be aware of their diagnosis and the limitations of the proposed treatments have access to supportive care and have suitable performance status according to assessment algorithms such as the one developed by Karnofsky or by the Eastern Cooperative Oncology Group ECOG . ECOG performance status 0 PS0 patients are without symptoms PS1 patients have mild symptoms not requiring treatment PS2 symptoms requiring some treatment PS3 disabling symptoms but allowing ambulation for 50 of the day PS4 ambulation 50 of the day. Only PS0 PS1 and PS2 patients are generally considered suitable for palliative noncurative treatment. If there is curative potential even poor-performance
