Four patients with advanced pancreatic adenocarcinoma suggesting slow-growing tumors are reported on. Tumors in 2 of the 4 were far-advanced, but both survived for over 3 years after treatment. One demonstrated 165 days of serum CA 19-9 level doubling time (T2CA 19-9), while the other demonstrated 135 days of DUPAN II level doubling time. Late tumor recurrence was observed in the remaining 2 patients who survived over 8 years after surgery, demonstrating long-term T2CA 19-9. A long-term T2CA 19-9 of 141 days was correlated with slow tumor growth in computed tomography (CT) scans in 1 patient, who survived 2.5 years after evidence of recurrent tumor without supplementary therapy. These observations, which suggest slow-growing variants, have not been reported in the literature on pancreatic adenocarcinoma. A significant difference was also seen in tumor-marker doubling time among 6 patients who survived over 3 years and 26 patients who did not (p = 0.02). Thus, the doubling time may characterize certain tumors biologically in a way that is useful in practice for predicting disease outcome.