To investigate clinical positioning between trastuzumab (Herceptin) monotherapy (H group) and combination therapy of trastuzumab and chemotherapy (H+CT group) based on a randomized controlled trial in women over 70 years with human epidermal growth factor receptor type-2 (HER2) positive primary breast cancer.

This study is a randomized, comparative trial of postoperative adjuvant therapies in women with HER2 (human epidermal growth factor receptor type-2)-positive primary breast cancer who are ≥70 years of age that will compare trastuzumab (Herceptin®) monotherapy (H group) and trastuzumab in combination with chemotherapy (H+CT group).

The objectives of this study are as follows.

1. To verify the clinical positioning of trastuzumab monotherapy and combined trastuzumab and chemotherapy as postoperative adjuvant therapies for the treatment of HER2-positive primary breast cancer patients who are ≥70 years of age.
2. To evaluate the safety of trastuzumab monotherapy and combined trastuzumab and chemotherapy in patients who are ≥70 years of age. In particular, to evaluate cardiac disorders that are a characteristic adverse drug reaction of trastuzumab as well as geriatric-related concerns including lipid metabolism, cerebral infarction and cognitive disorders.
3. To evaluate overall survival in patients who are ≥70 years of age using trastuzumab monotherapy or combined trastuzumab and chemotherapy.
4. To evaluate health-related quality of life (HRQOL), cost-effectiveness (utility), and conduct a comprehensive geriatric assessment (CGA) in patients who are ≥70 years of age and using trastuzumab monotherapy or combined trastuzumab and chemotherapy.
5. To establish and expand information networks by the participation of practitioners in clinical trials that are involved in general clinical practice and breast cancer.

Inclusion Criteria:

1. Histologically diagnosed as invasive breast cancer and received curative operation for primary breast cancer.

2. Stage: 1 (tumor size [pT] > 0.5 cm), 2A, 2B or 3A/ M0

3. Female between 70 and 80 years old

4. Primary region is HER 2 positive: either 3+ overexpression by IHC or positive by FISH

5. Baseline left ventricular ejection fraction (LVEF) is ≥55% measured by echocardiography or MUGA scan within 4 weeks before registration.

6. PS: 0-1 (ECOG)

7. Sufficient organ function meeting following criteria within 4 weeks before registration:

   • Leukocyte ≥2500 mm3
   • Neutrophil ≥1500 mm3
   • Platelet ≥100 000 mm3
   • Serum total bilirubin ≤2.0 x upper limit of normal (ULN)
   • ALT (GPT) or AST (GOT) ≤2.5 x ULN
   • Serum creatinine ≤2.0 x ULN
   • ALP ≤2.5 x ULN

8. No previous endocrine therapy or chemotherapy for breast cancer

9. Signed written informed consent

Exclusion Criteria:

1. Active multiple primary cancer (synchronous multiple primary cancer and invasive cancer of other organs)

2. Postoperative histological axillary lymph node metastasis ≥4

3. Axillary lymph node is not histologically evaluated

4. Histologically confirmed positive margin in breast conservation surgery (evaluation of margin status is based on policy of site)

5. History of drug-related allergy which could hinder planned treatment

6. Any history or complication of following cardiac disorders

   • History of congestive heart failure, cardiac infarction
   • Complication requires treatment such as: ischemic cardiac disorder, arrhythmia, valvular heart disease

7. Poorly controlled hypertension (ex. Systolic arterial pressure ≥180 mmHg or diastolic blood pressure ≥100 mmHg)

8. Poorly controlled diabetes

9. Continuous visit to a medial institution is considered difficult due to deterioration of activity of daily living (ADL)

10. Difficult to participate in the trial because of psychiatric disorder or psychiatric symptoms

11. Ineligible to the trial based on decision of an investigator