Japanese Journal of Clinical Oncology 32:108-109 (2002)
© 2002 Foundation for Promotion of Cancer Research
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Long-term Results of T1a, T1b and T1c Invasive Breast Carcinomas in Japanese Women: Validation of the UICC T1 Subgroup Classification
Breast Surgery Division, Department of Surgical Oncology, National Cancer Center Hospital, Tokyo, Japan
ABSTRACT
The objectives of this study were to investigate the long-term results of T1a, T1b and T1c Japanese invasive breast cancer patients defined by the UICC classification. The subjects were T1a (38), T1b (256) and T1c (1405) Japanese invasive breast cancer patients. Ten- and 20-year disease-free survival (DFS) and overall survival (OS) rates were analyzed by the UICC T1 subgroups (T1a, T1b, T1c). At 10 years, the respective DFS and OS rates of T1a, T1b and T1c patients were 91.9 and 91.9%, 86.1 and 86.8% and 82.4 and 83.9%, respectively. At 20 years, the respective DFS and OS rates of T1a, T1b and T1c patients were 70.7 and 70.7%, 76.7 and 76.7% and 69.1 and 70.1%. The differences of DFS and OS between T1a and T1c patients were not statistically significant. The DFS of patients with T1c breast carcinoma showed a statistically significant difference from that of T1b patients (p = 0.03). The validation of the T1 subgroup classification in Japanese breast cancer patients was confirmed, particularly for the T1c subgroup.
The objectives of this study were to investigate the long-term results of T1a, T1b and T1c invasive breast cancer defined by the UICC classification and to validate this subgroup classification in Japanese patients.
The T1 subgroup was subclassified according to the UICC criteria (Table 1) (1). This subclassification is widely accepted in Western countries (2).
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The study subjects were T1a (38), T1b (256) and T1c (1405) invasive breast cancer patients who underwent surgery between 1967 and 1995 at our hospital. The practicalities of the follow-up procedures have been reported previously (3). History and physical examinations, and also blood tests, were performed at least once every 6 months over 10 years. Blood tests included investigations of liver function and tumor markers (ST-439, CEA and CA15-3). Chest X-rays, abdominal ultrasound examinations and bone scintigrams were performed annually for 5 years. Patients with bilateral breast cancers (synchronous or asynchronous) or second primary malignancies were excluded from the analyses. Ten- and 20-year disease-free survival (DFS) and overall survival (OS) rates were analyzed and stratified by the UICC T1 subgroups (T1a, T1b, T1c). Survival curves were calculated by the Kaplan–Meier method (4). The log-rank test was used to estimate statistical differences (5).
At 10 years, the respective DFS and OS rates of T1a, T1b and T1c patients were 91.9 and 91.9%, 86.1 and 86.8% and 82.4 and 83.9%, respectively, and at 20 years, the respective DFS and OS rates of T1a, T1b and T1c patients were 70.7 and 70.7%, 76.7 and 76.7% and 69.1 and 70.1% (Figs 1 and 2). The differences of DFS and OS between T1a and T1c patients were not statistically significant. This was mainly because the number of patients in the T1a group was relatively small to detect the survival differences. Whereas the difference of OS between T1b and T1c patients was statistically marginal (p = 0.07), the DFS of patients with T1c breast carcinoma showed a statistically significant difference from that of T1b patients (p = 0.03). These data suggested that T1c could be defined as a high-risk category in the T1 group. In this series, most of the patients (1405/1699; 82.6%) were subclassified into the T1c group. We should therefore try to detect breast tumors of 1 cm or less. The introduction of mammography and ultrasonography into mass screening is thought to be useful for this purpose (6). The number of T1mic patients was so small that we could not analyze this category in the present study.
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In conclusion, even though the meaning of subclassification of T1a and T1b is questionable, these data support the validation of the T1 subgroup classification in Japanese breast cancer patients, particularly in the T1c group.
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FOOTNOTES
+ For reprints and all correspondence: Takashi Fukutomi, Department of Surgical Oncology, National Cancer Center Hospital, 1–1, Tsukiji 5-chome, Chuo-ku, Tokyo 104-0045, Japan. E-mail: tfukutom@gan2.ncc.go.jp 
REFERENCES
1 UICC. TNM Classification of Malignant Tumors. New York: Wiley-Liss 1997;123–30.
2 Rosen PP. Staging of breast carcinoma. In: Rosen PP, editor. Rosen’s Breast Pathology. Philadelphia: Lippincott Williams and Wilkins 2001:253–6.
3 Fukutomi T. Breast carcinoma-counterpoint. In: Johnson FE, Virgo KS, editors. Cancer Patient Follow-up, vol 3. St. Louis, MO: Mosby 1997; 315–9.
4 Kaplan EL, Meier P. Nonparametric estimation from incomplete observations. J Am Stat Assoc 1958;53:457–81.[Web of Science]
5 Peto R, Peto J. Asymptomatically efficient rank invariant test procedures. J R Stat Soc A 1972;135:185–98.
6 de Koning HJ. Commentary: assessment of nationwide cancer-screening programmes. Lancet 2000;355:80–1.[Web of Science][Medline]
Received August 30, 2001; accepted December 25, 2001.
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