Overexpression of HER2 is seen in about 20% of breast survival rates greater than 95%. Stage I includes women cancers. HER2 remains one of the best-characterized with smaller cancers and nodes either free of carcinoma examples of an effective therapy that is directed against a or with only very small micrometastases. Survival is tumor-specific molecular lesion. Before targeted therapy, ~86% at 10 years. Carcinomas are classified as Stage II which may take the form of blocking antibodies or small either because of larger tumor size or because of up to
Fig.19.30Ten-yearbreastcancerspecificsurvivalaccordingtoAJCCstageforER-positiveandER-negativecancers.Bothstageandbiologictypeofcancerareimportantdeterminantsofsurvival.ER-positiveinvasivecancershaveimprovedsurvivaloverER-negativecancersatallstages,butthisadvantagediminishesafter5yearsbecauseoflaterecurrencesofER-positivetumors.(Graph courtesy of Dr. Stephanie Wong; data from SEER-18,1992–2012.
http://seer.cancer.gov
Breast cancer specific survivalEstrogen receptor positive cancers (solid lines) Estrogen receptor negative cancers (dashed lines) Stage 0 Stage 1 Stage 2 Stage 3 Stage 4 0.2 0.4 0.6 0.8 1.0 http://ebooksmedicine.net three positive nodes. Survival declines to ~71% at Stage
II. Stage III is the group of locally advanced cancers defined by large size, involvement of skin or chest wall, or by four or more positive nodes. Only ~54% of patients survive 10 years. Stage IV is reserved for patients with distant metastases, and survival is very poor (~11%). The most likely site of a distant recurrence varies with the biologic type of cancer. Triple-negative cancers and HER2 cancers are more likely to metastasize to the brain and viscera, in contrast to ER-positive cancers, which most often metastasize to bones (
Table 19.7
Combining stage and biologic factors may provide a more accurate assessment of outcome. For example, for each cancer stage, the survival of patients with ER-positive cancers is higher than patients with ER-negative cancers 5 years postdiagnosis, especially for Stages III and IV (
Fig.
19.30 ). It must be noted, however, this advantage diminishes with time, with progressively smaller differences being seen at 10 years post-diagnosis and beyond (
Fig.
19.30 ). This narrowing of survival differences is explained by two factors. First, most deaths from ER-negative cancers happen within 5 years of diagnosis (
Fig. 19.31 ). Women who live beyond this point are those whose tumors have had excellent responses to treatment, and many of these women may be cured. Second, although the growth of ER-positive cancers is held in check for years by anti-estrogen therapy, this therapy is not curative and these cancers may eventually become resistant to treatment.
Historically, virtually all women with untreated breast cancer died within 3 to 4 years. However, great strides have been made in treatment and now 80% of women with breast cancer who receive optimal therapy will survive.
Endocrine therapy with tamoxifen and aromatase inhibitors is very effective for ER-positive cancers, which may remain dormant for many years.
Targeted therapy has the promise of being more effective and less toxic than conventional chemotherapy (
Table19.8TargetedTreatmentofBreastCancer