The role of stable disease in objective response assessment and its impacton survival in advance colorectal cancer: Is "stable disease" a homogenousresponse category?

Stable disease is a category which is not included in the evaluation of the overall treatment response rate. Tn many studies with a response rate belo w 20%, chemotherapy almost doubles the survival of patients. In the most ch emotherapy trials with advanced colorectal cancer patients, about 30-50% ha d stable disease. Despite belonging to the same category of therapy respons e, some patients with stable disease have achieved symptom improvement, but some have not. The aim of the study was to investigate whether the stabili zation of the disease with clinical benefit is associated with benefit in s urvival. A total of 99 patients with advanced colorectal cancer were treated with ca rboplatin (80 mg/m(2), day 1-7), 5-FU (750 mg/m2, day 1-5), leucovorin (100 mg/m(2), day 1-5) every 4 weeks. After 4 courses, in the: case of stable d isease (SD), the patients were stratified according to clinical benefit ach ievement in: Group A - patients with clinical benefit who continued with ch emotherapy until 8 cycles or until disease progression; group B - patients without clinical benefit in whom chemotherapy was stopped after 4 cycles. C linical benefit was a composite of assessment of pain,. ECOG performance st atus, weight and temperature. Clinical benefit required a sustained improve ment in at least one parameter without worsening in any other. Of 97 evaluable patients 48 achieved stable disease. Of 22 pts. with SD cli nical benefit performance status improvement was recorded in 17, pain relie f in 14, improvement in body weight in 14 and temperature disappearance in 8 pts. Of 26 pts. with SD without clinical benefit, 7 were asymptomatic fro m beginning of the chemotherapy. No difference was detected in the survival between responders and SD clinical benefit pts. (p = 0.24), but there was significant difference between responders and SD pts. without clinical bene fit (p = 0.0004). SD clinical benefit pts. had significant difference in su rvival in comparison to pts. with progressive disease (p = 5.1 x 10(-6)). The results of our study indicate that under category "stable disease" ther e are two different subpopulations of patients with quite different symptom response to chemotherapy, different time to progression and possible diffe rent survival.