Enzyme suggests breast cancer spread.

Enzyme suggests breast cancer spread

If high levels of an estrogen-induced enzyme show up in a surgically removed breast cancer, there's an increased chance the tumor has metastasized, spreading new growths elsewhere, a French study shows. Patients whose tumors contained high levels of the enzyme were three to four times more likely to develop a recurrence of the disease after surgery -- despite follow-up chemotherapy -- than women whose tumors had low enzyme levels, researchers report.

These findings hold out the prospect of better identifying which breast cancer patients face minimal risk of metastasis after surgery -- and therefore have little need for follow-up chemotherapy. Today, the best gauge of whether a breast cancer will recur is evidence that it spread to the lymph nodes before surgery. However, because roughly 30 percent of women whose lymph nodes appear disease-free at surgery eventually develop metastases, the National Cancer Institute last year recommended that all breast cancer patients receive chemotherapy.

Reported in the Nov. 11 LANCET, the new study followed 122 French breast cancer patients for four to five years after surgery. Researchers with Centre Rene Huguenin in Saint-Cloud and INSERM in Montpellier found tumor levels of cathepsin-D, a protein-digesting enzyme, particularly useful in flagging the metastatic potential of breast cancers that had not yet spread to the lymph nodes, whether or not the initial tumors were estrogen dependent. Patients whose tumors had high cathepsin-D levels and whose nodes appeared disease-free at the time of surgery were seven to 10 times more likely to develop postsurgical metastases than women whose tumors had spread to the nodes before surgery but contained scant cathepsin-D. Thus, the enzyme proved a stronger indicator of future metastasis risk in these women than did their lymph node status, says study coauthor Henri Rochefort of INSERM.

CAthepsin-D does seem a "promising metastatic marker," says Lance A. Liotta, head of pathology at the National Cancer Institute in Bethesda, Md. However, he adds, it is but one of a growing number of tumor markers ushering in the new field of "molecular prognosis."

William L. McGuire, head of medical oncology at the University of Texas Health Science Center at San Antonio, says he thinks the enzyme will prove most useful when evaluated as part of a battery of diagnostic factors. McGuire, who recently completed a study of 199 breast cancer patients with disease-free lymph nodes, says he found cathepsin-D worked best as a metastasis marker when coupled with an analysis of the amount of DNA in the tumor.