Recomendaciones

The location and stage of a tumor determine which the available treatment options can be adopted to treat the primary tumor. The therapeutic approach to be chosen depends largely on the TNM (tumor, node, metastasis) classification of the tumor:

• T describes the size of the original (primary) tumor and whether it has invaded nearby tissue,

• N describes nearby (regional) lymph nodes that are involved,

• M describes distant metastasis (spread of cancer from one part of the body to another).

Among the clinical options available, the most applied are surgical removal, chemother- apy, hormone therapy, immunotherapy and radiation therapy. These treatments may also be delivered as part of palliative care, where the aim is to improve the quality of life of the patient. In the following, these techniques are briefly summa- rized.

1.3.1 Surgery

Surgery was one of the first ways found to manage breast cancer. The most ancient evidence was found in an Edwin Smith papyrus dating from 3000 BC [9].

Surgery is the definitive treatment for breast cancer comprising either a breast (preferable) conserving operation, which removes the tumor with some surrounding tissue or mastectomy which involves removal of the whole breast. Both procedures are usually combined with sampling or removal of the axillary lymph nodes.

Historically, the treatment of breast cancer required mastectomy without excep- tion. Mastectomy removes all tumor cells including microscopic residual disease and provides staging information. Nowadays, following mastectomy an immediate or delayed reconstruction may be performed.

In the 1980s, large randomized trials compared the efficacy of breast conserving therapy (BCT), in the form of tumorectomy,sentinel node investigation, axillary node dissection, in case of positive sentinel node, and radiation, with modified radical mastectomy [10, 11]. In early stage breast cancer, BCT options have shown to offer equivalent overall survival to mastectomy, improved cosmetic results and reduced psychological trauma [12–14].

1.3.2 Chemotherapy

Preoperative chemotherapy can be offered to facilitate breast conservation in pa- tients with tumors of a significant size or in a location that made breast-conserving surgery unlikely to be done without a decrease in tumor size.

For patients with clinically uninvolved lymph nodes, sentinel lymph node biopsy and/or axillary nodal dissection generally is performed before initiation of neoad- juvant chemotherapy.

Patients at risk of distant metastasis are generally administered adjuvant chemother- apy, in accordance to the actual guidelines. Results of the Early Breast Cancer Trialists’ Collaborative Group meta-analysis have shown that adjuvant chemother- apy improves breast cancer specific survival and overall survival [15].

1.3.3 Hormone therapy

Hormonal therapy is one of the major modalities of medical treatment for cancer. It involves the manipulation of the endocrine system through exogenous adminis- tration of specific hormones, particularly steroid hormones, or drugs which inhibit the production or activity of such hormones (hormone antagonists). Steroid hor- mones are powerful drivers of gene expression in certain cancer cells, changing the activity of certain hormones and therefore possibly causing certain cancers to cease growing, or even undergo cell death. Surgical removal of endocrine organs, such as oophorectomy can also be employed as a form of hormonal therapy.

Typically, the hormonal treatment is performed after surgery and it is not recom- mended concomitantly with chemotherapy.

Hormonal therapy is used for several types of cancers derived from hormonally responsive tissues, including the breast. One of the most frequent example of hor- monal therapy in oncology is the use of the selective estrogen-response modulator (SERM), tamoxifen, for the treatment of breast cancer, although another class of hormonal agents, such as aromatase inhibitors, have an expanding role in this disease.

1.3.4 Radiation therapy

Radiotherapy (RT) in the breast cancer is a loco-regional technique, generally integrating the treatment after conserving surgery or after mastectomy when in respecting specific criteria, in order to eliminate the microscopic residual disease and to prevent local relapse. According to Holland et al [16], the surgical tumor bed and the mammary gland risk that contain microscopic disease must be re- moved with the breast conserving surgery and it is essential to irradiate locally to eradicate the residual disease. This technique is usually applied 4 weeks after surgery, after the healing. RT after surgery has proven efficacy with equivalent or superior free disease survival, when compared to mastectomy [12, 13, 17–19]. Several studies confirmed that surgery followed by RT reduces mortality among breast cancer women, 5 to 10 years after, being therefore essential to protect the normal tissues, keeping the severity of the secondary effects as low as possible [12, 13, 20].

The choice of the irradiation technique (external beam RT or brachytherapy), the dose to administer to the tumor depend on its location, size, histology, grade

Table 1.1: Breast cancer five-year survival by stage at diagnosis.

and extension of the disease, the breast size, cosmetic expected result or patient preference. Adding an extra dose (frequently called a boost) either with photons or electrons, to the tumor bed, as determined from mammographic and surgical information, further reduces the risk of local relapse.

In the last years, with the growth and broader know-how of the biology and nature of the breast tumors, combined with the technological improvements in immobi- lization accessories (breast board, vacuum bed, etc), planning in 3-dimensional computed tomography (CT) images, the positioning verification imaging, permit- ted a great improvement in precision and reproducibility of the patient set up, in the definition of the target volumes and homogeneity of the dose distributions. The modern linacs are now equipped with complex collimator systems that permit a better field size control as well as modeling the beam intensity, conforming the dose distribution to the volumes to treat.

The goal of RT it is to adequately irradiate all the mammary gland, in initial stage breast cancer patients while trying to minimize the dose to the adjacent organs at risk (OAR).