Incorporating Tumor Characteristics to the American Joint Committee on Cancer Breast Cancer Staging System

• Published in: The oncologist (Dayton, Ohio) Vol. 22; no. 11; pp. 1292 - 1300
• Main Authors: Chavez‐MacGregor, Mariana, Mittendorf, Elizabeth A., Clarke, Christina A., Lichtensztajn, Daphne Y., Hunt, Kelly K., Giordano, Sharon H.
• Format: Journal Article
• Language: English
• Published: England AlphaMed Press 01-11-2017
• Subjects: Breast Cancer; Breast Neoplasms - classification; Breast Neoplasms - epidemiology; Breast Neoplasms - genetics; Breast Neoplasms - pathology; Disease-Free Survival; Female; Humans; Neoplasm Metastasis; Neoplasm Staging; Prognosis; Proportional Hazards Models; Receptor, ErbB-2 - genetics; Receptors, Estrogen - genetics; Risk Factors; Staging system; Survival Rate; Tumor characteristics; United States - epidemiology; Tumor characteristics; Breast cancer; Staging system; Prognosis
• ISSN: 1083-7159; 1549-490X
• DOI: 10.1634/theoncologist.2017-0116

Background
The American Joint Committee on Cancer (AJCC) breast cancer staging system provides important prognostic information. The recently published eighth edition incorporates biological markers and recommends the use of a complex “prognostic stage.” In this study, we assessed the relationship between stage, breast cancer subtype, grade, and outcome in a large population‐based cohort and evaluated a risk score system incorporating tumor characteristic to the AJCC anatomic staging system.
Materials and Methods
Patients diagnosed with primary breast cancer stage I–IV between 2005–2008 were identified in the California Cancer Registry. For patients with stage I–III disease, pathologic stage was recorded. For patients with stage IV disease, clinical stage was utilized. Five‐year breast cancer specific survival (BCSS) and overall survival (OS) rates were determined for each potential tumor size‐node involvement‐metastases (TNM) combination according to breast cancer subtype. A risk score point‐based system using grade, estrogen receptor, and human epidermal growth factor receptor 2 (HER2) status was designed to complement the anatomic AJCC staging system. Survival probabilities between groups were compared using log‐rank test. Cox proportional hazards models were used.
Results
Among 43,938 patients, we observed differences in 5‐year BCSS and OS for each TNM combination according to breast cancer subtype. The most favorable outcomes were seen for hormone receptor‐positive tumors followed closely by HER2‐positive tumors, with the worst outcomes observed for triple negative breast cancer. Our risk score system separated patients into four risk groups within each stage category (all p < .05).
Conclusion
Our simple risk score system incorporates biological factors into the AJCC anatomic staging system, providing accurate prognostic information.
Implications for Practice
This study demonstrates that stage, but also breast cancer subtype and grade, define prognosis in a large population of breast cancer patients. It shows that a point‐based risk score system that incorporates these biological factors provides refined stratification and information on prognosis, improving the anatomic American Joint Committee on Cancer (AJCC) staging system. In addition, the overall mortality and breast cancer specific mortality rates detailed here provide much‐needed information about prognosis in the current era, refining the current AJCC staging.
摘要
背景. 美国癌症联合委员会（AJCC）乳腺癌分期系统提供了重要的预后信息。最近发表的AJCC第八版乳腺癌分期系统纳入了生物标志物, 并推荐使用复杂的”预后分期”。在本研究中, 我们在一项大型人群队列研究中评估了分期、乳腺癌亚型、分级和结局之间的关系, 并评价一种将肿瘤特征整合到AJCC解剖学分期系统的风险评分系统。
材料和方法. 在加利福尼亚癌症登记处确定了2005年至2008年期间被诊断为I‐IV期原发性乳腺癌的患者。对于I‐III期疾病的患者, 记录病理分期。对于IV期疾病的患者, 采用临床分期。根据乳腺癌亚型, 确定了每个潜在肿瘤大小‐结节转移（TNM）组合的五年乳腺癌特异性生存率（BCSS）和总生存率（OS）。设计了采用分级、雌激素受体和人表皮生长因子受体2（HER2）状态的基于点风险评分系统, 旨在补充解剖学AJCC分期系统。采用log‐rank 检验比较了组间的生存概率。采用了Cox比例风险回归模型。
结果. 在43 938例患者中, 我们观察到了根据乳腺癌亚型分类的每个TNM组合的5年BCSS和OS的差异。观察到激素受体阳性肿瘤的结局最有利, 其次为HER2阳性肿瘤, 三阴性乳腺癌的结局最差。我们的风险评分系统在每个分期类别中将患者分成了四个风险组（所有p<0.05）。
结论. 我们的简单风险评分系统将生物学因素纳入AJCC解剖学分期系统, 提供了准确的预后信息。
The American Joint Committee on Cancer (AJCC) breast cancer staging system provides important prognostic information. The recently published eighth edition incorporates biological markers and recommends the use of a complex prognostic stage. In this study, the relationship between stage, breast cancer subtype, grade, and outcome in a large population‐based cohort is assessed, and a risk score system incorporating tumor characteristic to the AJCC anatomic staging system is evaluated.