Celecoxib and Trastuzumab in Treating Women With Metastatic Breast Cancer

DISEASE CHARACTERISTICS: * Histologically proven metastatic breast cancer * HER2/neu-positive (overexpressing) tumor tissue * Failed prior trastuzumab (Herceptin) therapy with or without chemotherapy * Resected stage IV disease allowed if evidence of disease * Bidimensionally measurable or evaluable disease * No lesions in previously irradiated field except nonbone lesions progressive after radiotherapy * No pleural effusions * No blastic or mixed bony metastases * No palpable abdominal masses * No leptomeningeal disease * Brain metastases allowed if: * No concurrent use of steroids * At least 3 months since prior brain irradiation * No evidence of progression of metastases * Hormone receptor status: * Not specified PATIENT CHARACTERISTICS: Age: * 18 and over Sex: * Female Menopausal status: * Not specified Performance status: * Karnofsky 70-100% Life expectancy: * At least 3 months Hematopoietic: * Granulocyte count at least 1,500/mm\^3 * Hemoglobin at least 8.0 g/dL * Platelet count at least 100,000/mm\^3 Hepatic: * AST/ALT no greater than 2 times upper limit of normal (ULN) * Bilirubin no greater than 1.5 times ULN Renal: * Creatinine no greater than 1.5 mg/dL Cardiovascular: * LVEF at least 50% Other: * Not pregnant * Negative pregnancy test * Fertile patients must use effective barrier contraception * No other prior malignancy within the past 5 years except adequately treated carcinoma in situ of the cervix or nonmelanoma skin cancer * No other serious medical illness * No severe infection * No severe malnutrition * No prior allergic reactions to sulfonamides or celecoxib PRIOR CONCURRENT THERAPY: Biologic therapy: * See Disease Characteristics * Prior trastuzumab (Herceptin) for breast cancer allowed, either as adjuvant/neoadjuvant or for metastatic disease Chemotherapy: * See Disease Characteristics * At least 4 weeks since prior chemotherapy (6 weeks for nitrosoureas or mitomycin) and recovered * Prior cytotoxic therapy for breast cancer allowed, either as adjuvant/neoadjuvant or for metastatic disease Endocrine therapy: * See Disease Characteristics * At least 3 weeks since prior hormonal therapy * Prior exogenous hormonal therapy for stage IV disease and/or as adjuvant therapy allowed Radiotherapy: * See Disease Characteristics * At least 4 weeks since prior radiotherapy and recovered * Prior localized radiotherapy allowed if no influence on the signal measurable lesion * Concurrent localized radiotherapy allowed if no influence on the signal measurable lesion Surgery: * See Disease Characteristics * At least 3 weeks since prior major surgery and recovered * At least 2 weeks since prior minor surgery and recovered