Commonly used criteria for response evaluation during cancer treatment

A complete response is defined as disappearance of all evidence of disease and a paial response as >50% reduction in the sum of the products of the perpendicular diameters of all measurable lesions. The determination of paial response may also be based on a 30% decrease in the sums of the longest diameters of lesions (Response Evaluation Criteria in Solid Tumors ). Progressive disease is defined as the appearance of any new lesion or an increase of >25% in the sum of the products of the perpendicular diameters of all measurable lesions (or an increase of 20% in the sums of the longest diameters by RECIST). Tumor shrinkage or growth that does not meet any of these criteria is considered a stable disease. Some sites of involvement (e.g. bone) or patterns of involvement (e.g.lymphangitic lung or diffuse pulmonarg infiltrates) are considered unmeasurable.Reference: Harrison; 19th edition