Overview

The American Cancer Society estimates that 234,190 Americans will be diagnosed with invasive breast cancer and 40,730 will die of the disease in the United States in 2015.  

Breast cancer is the most frequently diagnosed cancer globally and is the leading cause of cancer-related death in women.山东省肿瘤医院呼吸肿瘤内科张品良

The lifetime risk for breast cancer for women in the United States has increased from 1 in 11 in the 1970s to 1 in 8 today, a change related to shifting breast cancer risk factor demographics and the increased use of screening mammography. 

Breast cancer incidence peaked around 2000 then decreased to current rates with some variation among racial and socioeconomic groups.

Between 2006 and 2010, breast cancer incidence increased slightly among African American women, decreased among Hispanic women, and was stable among whites, Asian Americans/Pacific Islanders, and American Indians/Alaska Natives.

Historically, white women have had the highest breast cancer incidence rates among women aged 40 years and older; however, incidence rates are converging among white and African American women, particularly among women aged 50 years to 59 years.

Since 1991, breast cancer mortality has been declining suggesting a benefit from the combination of early detection and more effective treatment.

The etiology of the vast majority of breast cancer cases is unknown.

However, numerous risk factors for the disease have been established.

These risk factors include: female gender; increasing patient age; family history of breast cancer at a young age; early menarche; late menopause; older age at first live childbirth; prolonged hormone replacement therapy; previous exposure to therapeutic chest wall irradiation; benign proliferative breast disease; increased mammographic breast density; and genetic mutations such as of the BRCA1/2 genes.

However, except for female gender and increasing patient age, these risk factors are associated with only a minority of breast cancers.

Women with a strong family history of breast cancer should be evaluated according to the NCCN Guidelines for Genetic/Familial High-Risk Assessment: Breast and Ovarian.

Women at increased risk for breast cancer (generally those with ≥1.7% 5-year risk for breast cancer using the Gail model of risk assessment) may consider risk reduction strategies (see NCCN Guidelines for Breast Cancer Risk Reduction).

Proliferative abnormalities of the breast are limited to the lobular and ductal epithelium.

In both the lobular and ductal epithelium, a spectrum of proliferative abnormalities may be seen, including hyperplasia, atypical hyperplasia, in situ carcinoma, and invasive carcinoma.

Approximately 85% to 90% of invasive carcinomas are ductal in origin.

The invasive ductal carcinomas include unusual variants of breast cancer, such as mucinous, adenoid cystic, and tubular carcinomas, which have especially favorable natural histories.

讨论 

概述 

美国癌症协会估计在2015年美国将有234190例美国人被诊断为侵袭性乳腺癌且40730例将死于该疾病。

乳腺癌是全球最常见的癌症并且是女性肿瘤相关死亡的主要原因。

美国女性一生中患乳腺癌的风险从上个世纪七十年代的1/11升高至现在的1/8，这一变化与乳腺癌危险因素人口资料改变和筛查乳腺摄影的应用增加有关。

乳腺癌发病率大约在2000年达到高峰然后降低至当前的发病率，在不同种族与社会经济群体当中具有一些差异。

在2006年与2010年间，乳腺癌发病率在非洲裔美国女性当中略有升高，在西班牙女性当中降低，而在白种人、亚裔美国人/太平洋岛民以及美国印地安人/阿拉斯加当地人当中稳定。

历史上，在40岁及以上女性当中白人女性乳腺癌发病率最高；但是，在白种人与非洲裔美国女性特别是年龄50至59岁女性当中发病率逐渐一致。

自1991年以来，乳腺癌死亡率已经下滑提示从早期发现与更有效的治疗中受益。

绝大多数乳腺癌病例的病因不明。

但是，该疾病很多的危险因素已公认。

这些危险因素包括：女性性别；患者年龄增加；在年轻时乳腺癌家族史；月经初潮早；绝经晚；初次分娩时年龄较大；长期的激素替代治疗；既往治疗性胸壁照射；乳腺良性增生性疾病；乳房摄影乳腺密度增加；以及诸如BRCA1/2基因遗传突变。

但是，除了女性性别和患者年龄增加之外，这些危险因素只与少数乳腺癌有关。

有明显乳腺癌家族史的女性应该按照遗传性/家族性高危性评估：乳腺与卵巢NCCN指南进行评估。

在女性乳腺癌风险增加时(通常是那些利用Gail风险评估模型乳腺癌5年风险≥1.7%者)可以考虑降低风险的策略(见NCCN降低乳腺癌风险指南)。

乳腺异常增生仅限于小叶和导管上皮。

在小叶和导管上皮中都可能见到各种各样的增殖异常，包括增生、非典型增生、原位癌以及侵袭癌。

大约85%至90%的浸润性癌是导管来源。

浸润性导管癌包括罕见的乳腺癌变种，如粘液性癌、腺样囊性癌和管状癌，其具有特别有利的自然发展过程。