Lucy Wortham James Lecture. Subclinical disease.

A number of patients with cancer later develop metastases in the draining lymphatics, which initially were clinically negative. These occult deposits represent subclinical disease in lymphatic areas accessible to palpation, like the neck, axillae, and groin. The concept applies also to the microscopic disease left in an area after a surgical procedure is known to have removed all gross cancer, yet some patients later develop a recurrence. The term "subclinical disease" refers only to disease in a specific anatomic area, based on clinical facts. Radiobiological parameters account for the fact that subclinical disease requires less irradiation to be eradicated than gross cancer. The concept has two main applications, elective irradiation of clinically negative peripheral lymphatics and locoregional irradiation combined with surgery, which are determined by site and disease. The concept of subclinical disease also has implications for chemotherapy, which bear a direct relationship between chemotherapy both with radiation therapy and surgery.