Risk of breast cancer in symptomatic women in primary care: a case–control study using electronic records

Abstract

<h3>Background</h3> Breast cancer is the most common cancer in the UK. GPs are encouraged to refer all women whose symptoms may represent cancer, rather than selecting those at highest risk. <h3>Aim</h3> To identify and quantify features of breast cancer in primary care. <h3>Design and setting</h3> A UK case–control study using the Clinical Practice Research Database (CPRD). <h3>Method</h3> Possible features of breast cancer were identified in the year before diagnosis, and odds ratios calculated using conditional logistic regression. Positive predictive values (PPVs) were estimated for consulting women. <h3>Results</h3> A total of 3994 women aged ≥40 years with breast cancer between 2000 and 2009, and 16 873 age-, sex-, and practice-matched controls were studied. Median age at diagnosis was 63 years (interquartile range 55–74 years). Four features were significantly associated with breast cancer: breast lump (odds ratio [OR] 110; 95% confidence interval [CI] = I88 to150), breast pain (OR = 4.2; 95% CI = 3.0 to 6.0), nipple retraction (OR = 26; 95% CI = 10 to 64), nipple discharge (OR = 19; 95% CI = 8.6 to 41): all <i>P</i>-values &lt;0.01. In the year before diagnosis, 1762 (44%) of cases had a breast lump compared with 132 (0.8%) controls. The PPV of breast cancer with a breast lump was 4.8% in women aged 40–49 years, rising to 48% in women aged &gt;70 years. PPVs were lower in women who also reported breast pain. <h3>Conclusion</h3> Generally, the figures support current referral practice. However, the low likelihood of cancer for all the non-lump symptoms means that the current guidance recommends investigation for possible cancer at a more liberal risk threshold than for other cancers. Although supported by patients, this may not meet current NHS criteria for cost–benefit.