Supplementary Material for: The impact of breast awareness on the early detection of breast cancer in young women: A systematic review

Background ‘Breast awareness’ is a recommendation that women understand the symptoms of breast cancer and become familiar with the usual look and feel of their breasts. It is recommended for women of all ages in breast cancer screening guidelines around the world. The objective of this study was to assess the evidence for breast awareness by investigating its effect on breast cancer outcomes in women of pre-mammographic-screening age (under age 40), at average risk of breast cancer. Methods A systematic review was performed using PRISMA methodology. Following the search, abstracts and full text articles were assessed against eligibility criteria. Data were extracted into evidence tables, risk of bias was assessed, narrative synthesis was performed and results were described. Eligible studies were original research studies assessing the impact of breast awareness on cancer outcomes (such as stage at diagnosis or survival) in women ≤40. Medline, PubMed and Cochrane Library were searched. Results After screening the 6,204 abstracts identified in the search, no studies meeting all eligibility criteria were found. Two partially eligible studies were identified. These met the intervention and outcomes criteria but included mixed-age cohorts that included but were not limited to women ≤40. These studies provided low-level (Level IV) evidence of moderate quality that there is some benefit (earlier stage at diagnosis and/or improved survival) of breast awareness in a mixed-age cohort that included some younger women. Conclusions No studies evaluating the impact of breast awareness exclusively in young women were identified. Limited evidence of benefit of breast awareness was found. Guidelines that recommend breast awareness should be reviewed and qualified with an explanation that the evidence of benefit is weak. Women have limited screening options available to them for the early detection of breast cancer until they reach mammographic screening age. The study was registered on Prospero (ID: CRD42021279457).背景：乳房知晓（Breast awareness）是一项倡议，旨在让女性了解乳腺癌相关症状，并熟悉自身乳房的正常外观与触感。全球范围内的乳腺癌筛查指南均建议所有年龄段女性践行此项举措。本研究旨在评估乳房知晓的相关证据，通过探究其对钼靶筛查前年龄段（40岁以下）、乳腺癌平均风险女性的乳腺癌转归产生的影响。 方法：本研究采用系统评价与Meta分析优先报告条目（PRISMA）方法开展研究。检索完成后，依据入选标准对检索得到的摘要及全文文献进行评估。将数据提取至证据表格中，开展偏倚风险评估、描述性综合分析，并对结果进行阐述。合格研究为评估乳房知晓对≤40岁女性癌症转归（如诊断分期或生存率）影响的原创性研究。本研究检索了Medline、PubMed及考克兰图书馆（Cochrane Library）数据库。 结果：在对检索得到的6204篇摘要进行筛查后，未发现符合全部入选标准的研究。仅识别出2篇部分符合标准的研究。此类研究满足干预措施与结局指标的要求，但纳入的混合年龄队列中包含（但不限于）≤40岁的女性。上述研究提供了中等质量的低级别（IV级）证据，表明在纳入部分年轻女性的混合年龄队列中，乳房知晓可带来一定获益（诊断分期更早和/或生存率提升）。 结论：未发现仅针对年轻女性评估乳房知晓影响的研究。目前仅存在有限的乳房知晓获益证据。建议对推荐乳房知晓的指南进行修订，并附加说明指出其获益证据等级较低。女性在达到钼靶筛查年龄前，可用于乳腺癌早期检测的筛查手段较为有限。本研究已在国际前瞻性系统评价注册平台（Prospero）注册（注册号：CRD42021279457）。