Prognostic significance of S-phase fraction in good-risk, node-negative breast cancer patients.
OBJECTIVE
Formalin-fixed, paraffin-embedded tissues from axillary node-negative breast cancer patients were analyzed by flow cytometry to determine the prognostic significance of DNA ploidy and S-phase fraction (SPF).


METHODS
All patients were registered on a good-risk control arm of an intergroup clinical trial. They had small- to intermediate-sized (less than 3 cm), estrogen receptor (ER)-positive tumors and received no adjuvant therapy after modified radical mastectomy or total mastectomy with low axillary-node sampling. The median follow-up was 4.8 years.


RESULTS
Assessable ploidy results were obtained from 92% of the 298 specimens studied (51% diploid, 49% aneuploid), and SPFs were assessable for 83% of the tumors. SPFs for diploid tumors ranged from 0.7% to 11.9% (median, 3.6%), compared with a range of 1.2% to 26.7% (median, 7.6%) for aneuploid tumors (P less than .0001). No significant differences in disease-free or overall survival were observed between patients with diploid and aneuploid tumors. Using different SPF cutoffs by ploidy status (4.4% for diploid, 7.0% for aneuploid), patients with low SPFs had significantly longer disease-free survival rates than patients with high SPFs (P = .0008). The actuarial 5-year relapse rates were 15% and 32% for patients with low (n = 142) and high SPFs (n = 105), respectively. Similar relationships between SPF and clinical outcome were observed for patients with diploid tumors (P = .053) and for patients with aneuploid tumors (P = .0012).


CONCLUSIONS
S-phase fraction provides additional prognostic information for predicting disease-free survival for axillary node-negative breast cancer patients with small, ER-positive tumors.
Clark
G M
GM
University of Texas Health Science Center, San Antonio 78284-7884.
Mathieu
M C
MC
Owens
M A
MA
Dressler
L G
LG
Eudey
L
L
Tormey
D C
DC
Osborne
C K
CK
Gilchrist
K W
KW
Mansour
E G
EG
Abeloff
M D
MD
D000206:Actuarial Analysis; D001706:Biopsy; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology; D004273:DNA, Neoplasm / Q000235:genetics*; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D011003:Ploidies; D011379:Prognosis; D016196:S Phase; D016019:Survival Analysis
D004273:DNA, Neoplasm