Elevated serum cathepsin B1-like activity in women with neoplastic disease

Activities of selected hydrolytic enzymes were assessed in blind-coded sera of 121 women with invasive cancer of various organs. Acetylglucosaminidase, β-glucuronidase, and alkaline phosphatases were not markedly elevated above controls. In contrast, cathepsin B1-like (CB1) activity in sera before therapy averaged 45-fold greater than that of 56 normal controls ( P < 0.001) and 95% of the values exceeded 0–20 units, the levels characteristic of 95% of healthy controls. CB1 also increased progressively during transition from preinvasive to invasive squamous cervical carcinoma ( P < 0.001). Patients with recurrent or Stages III–IV disease had higher CB1 levels than those with Stages I–II tumors ( P < 0.02). In women with gynecologic cancer who showed objective remissions to surgery or chemotherapy, mean pretreatment levels of CB1 fell from 226 and 330 units, respectively, to normal within 12–38 days of surgery or ca. 4 months of chemotherapy. CB1 remained elevated when tumors were refractory to treatment. Subjects with inflammatory, degenerative, or other non-neoplastic disease showed no CB1 elevation, but CB1 was enhanced in women with endometriosis or endometrial hyperplasia. A generalized increase in serum acid and alkaline hydrolases, including CB1, was found in advanced pregnancy. Although the nature of the increments in CB1-like activity in cancer remains to be determined, such analyses may help supplement present methods of physical diagnosis.