STAGE I BREAST CANCER
Stage I breast cancer ranges from microinvasive tumors (≤ 0.1 cm) to tumors ≤ 2 cm without evidence of spread to the regional lymph nodes.
Pathology of invasive breast cancer
Ductal carcinoma
Most cases of invasive carcinomas of the breast are ductal in origin. Of the different histologic subtypes of ductal carcinoma that have been described, tubular, medullary, mucinous (colloid), and papillary subtypes have been associated with a favorable outcome.
Lobular carcinoma
Approximately 5% to 10% of invasive breast cancers are lobular in origin. This histology has been associated with synchronous and metachronous contralateral primary tumors in as many as 30% of cases.
Treatment
Surgical and radiation treatments
Multiple studies have demonstrated that patients with stage I breast cancer who are treated with either breast-conserving therapy (lumpectomy and radiation therapy) or modified radical mastectomy have similar disease-free and overall survival rates.
Breast-conserving therapy
Extent of local surgery The optimal extent of local surgery has yet to be determined and, in the literature, has ranged from excisional biopsy to quadrantectomy. A consensus statement on breast-conserving therapy issued by the NCI recommended that the breast cancer be completely excised with negative surgical margins.
The extent of axillary surgery also continues to evolve. In recent years, patients with early-stage breast cancer who have clinically node-negative disease have the option to undergo sentinel lymph node biopsy rather than axillary node dissection. The present standard of care for patients with a positive sentinel node is complete nodal dissection. A study is under way to determine whether patients with a positive sentinel node require further axillary surgery.
Patient selection Specific guidelines must be followed when selecting patients for breast conservation. Patients may be considered unacceptable candidates for conservative surgery and radiation therapy either because the risk of breast recurrence following the conservative approach is significant enough to warrant mastectomy or the likelihood of an unacceptable cosmetic result is high. Some patients who are candidates for breast conservation can undergo breast MRI to identify sites of additional disease within the breast that may preclude breast-conserving treatment, although this is not a standard for evaluation. Contraindications to breast-conserving surgery are listed in Table 1.
Risk factors for ipsilateral recurrence For patients undergoing conservative surgery followed by radiation therapy to the intact breast, the risk of ipsilateral breast tumor recurrence has been reported to range from 0.5% to 2.0% per year, with long-term failure rates varying from 7% to 20%. Risk factors for ipsilateral breast tumor recurrence include, but are not limited to, young age (< 35 to 40 years), an extensive intraductal component, major lymphocytic stromal reaction, peritumoral invasion, presence of tumor necrosis, and positive resection margins. After a wide excision has been performed, the specimen should be oriented and inked; the pathologist may then ink each margin a different color. If a positive surgical margin is present, the color-coded system will guide the reexcision to obtain negative surgical margins with the removal of the least amount of breast tissue possible.
Earlier studies demonstrated that an extensive intraductal component was a risk factor for local relapse. However, in subsequent reports, when negative surgical margins were achieved, patients with an extensive intraductal component could be safely treated with breast conservation. Although it is desirable to achieve negative surgical margins, the available data do not preclude the use of conservative treatment, provided that adequate radiation doses (> 6,000 cGy) to the tumor bed are employed. The role of the remaining risk factors previously cited in predicting recurrence is unclear, and patients should not be denied breast conservation because of their presence.
