Sept. 1, 2004 — Women who have breast cancer detected by mammography
screening have a reduced risk of distant tumor recurrence than women with breast
cancer detected outside of screening, according to a study in the Sept. 1 issue
of the Journal of the American Medical Association (JAMA).
The
incidence of cancerous tumors detected by mammography screening is increasing
due to its expanding use, according to background information in the article.
Selection of therapies for women diagnosed as having breast cancer is based on
risk estimations for cancer recurrence.
Heikki Joensuu, M.D., of Helsinki
University Central Hospital, Helsinki, Finland, and colleagues compared the
survival outcomes of women with cancerous tumors detected by mammography
screening with women whose tumors were detected outside of screening. The study
included 2,842 women identified from the Finnish Cancer Registry as having
breast cancer in 1991 or 1992. The average follow-up time was 9.5 years. The
clinical, histopathological and biological features of the tumors were
compared.
The researchers found that women with cancerous tumors detected
by mammography screening had better estimated 10-year distant (other location in
the body) disease-free survival than women with tumors found outside of
screening. In analysis that included factors related to the biological aspects
of the cancers, women with tumors detected outside of screening had a 90 percent
increased risk for distant recurrence than women with tumors detected by
mammography screening.
"Cancerous tumor detection in mammography
screening was a favorable prognostic variable independent of the number of
axillary lymph nodes, the primary tumor size, age at cancer detection, and the
histological grade," the authors write. "Further research on factors related to
cancer invasiveness and metastasis formation needs to be performed. For women
with cancerous tumors detected by mammography screening, the risk of distant
metastases may be overestimated unless the method of detection is taken into
account in risk estimations."
Editor's Note: This work was supported by
grants from the Helsinki University Central Hospital Research Funds, Sigrid
Juselius Foundation, Yamanouchi European Foundation, and the Cancer Society of
Finland.
Editorial: Do Tumors Detected by Mammography Screening Have a
Favorable Prognosis?
In an accompanying editorial, Ruth M. O'Regan,
M.D., of the Winship Cancer Institute, Emory University, Atlanta, writes that
until further data area available, clinicians and researchers must use available
prognostic and predictive factors to determine the best adjuvant (additional)
treatment, if any, for patients with breast cancer."Joensuu et al identified a
group of patients with small, node-negative breast tumors that are detected by
mammography screening and who have a risk of distant recurrence or death due to
breast cancer of less than 10 percent at 10 years. In the United States,
patients younger than 70 years with tumors measuring between one and two cm
would likely be offered systemic therapy. In addition, some data suggest that
adjuvant therapy can improve outcome in patients with even smaller tumors.
Therefore, these results, if confirmed, could help determine which patients
would truly benefit from systemic therapy. Although newer screening techniques,
such as breast magnetic resonance imaging, are being actively investigated,
these data suggest that mammography screening may more than a useful, acceptable
screening tool — it may actually select for patients with a favorable
prognosis."
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