BACKGROUND AND PURPOSE:

• Interval cancers are those that are diagnosed after receiving a ‘negative screen’ mammography report, but before the next recommended screening examination
• 15% of breast cancers are ‘interval cancers’ and include
  • Cancers that were missed on the initial ‘negative screen’
  • Rapid growing cancers that were not present on the initial screen and present due to symptoms (e.g. detecting a lump) which tend to be poorer prognosis
  • McCarthy et al. (JAMA Oncology, 2018) sought to identify women who were at higher risk for a poor prognosis (latter group) with interval cancer

METHODS:

• Mammogram data was collected from the Population-Based Research Optimizing Screening Through Personalized Regimens (PROSPR) consortium
• Participants: Women ≥40 years with no earlier diagnosis of breast cancer who received screening mammography and negative screening results (BI-RADS 1 or 2)
• Cancer diagnoses within 1 year after screening mammography were obtained from state cancer registries
• Poor prognosis breast cancers were defined as
  • Distant metastases | Cancer-positive regional lymph nodes | Estrogen receptor–positive and/or progesterone receptor–positive and HER2-negative invasive cancer 2 cm or more in diameter | Eestrogen receptor–negative, progesterone receptor–negative, HER2-negative (triple-negative) invasive cancer 1 cm or more in diameter | HER2-positive invasive cancer 1 cm or more in diameter
• Association of age, breast density, and family history with cancer diagnosis was assessed using logistic regression analysis

RESULTS:

• 306,028 women were included in the study
  • 272,881 women had a negative screening result
  • Only 160 women (5.9 per 10,000) had a cancer within 1 year of negative screening mammography
• Interval cases were more likely to have poor prognosis compared to positive mammography cases (43.8% v. 26.9% )
• Among all women with negative mammography results
  • Women with dense breasts were twice as likely to receive a cancer diagnosis vs nondense breasts (odds ratio [OR] of 2.07; 95% CI,1.48-2.89 (P = .02)
  • Age and family history were not associated with greater likelihood of cancer diagnosis
• Among those with interval breast cancer, younger women (40-49 years) were more likely to receive poor prognosis than older women (70-89 years)
  • OR of 3.52; 95% CI, 1.15-10.72; (P= .048; P for trend = .005)
• Breast density and family history were not associated with poor prognosis interval cancers
• In cases with positive mammogram results, positive predictive value for subsequent cancer diagnosis depended on older patient age and positive family history but not breast density
  • 40-49 years vs those 70-89 years: OR, 0.22; 95% CI, 0.18-0.26 (P < .001)
  • Positive family history: OR, 1.29; 95% CI, 1.12-1.48 (P < .001)
  • None of these factors were associated with poor prognosis

CONCLUSION:

• The chance of having an interval cancer is small but more likely to be associated with a poor prognosis
• Breast density is predictive of an interval cancer but not whether the cancer will have a poor prognosis
• Younger women were more at risk to receive a poor prognosis with an interval cancer than older women
  • More likely to be rapidly growing vs slower growing cancers that are more typically seen in older women
• While breast density increases breast cancer risk, including other factors such as age may be helpful in identifying women at higher risk for poor prognosis interval breast cancer

Learn More – Primary Sources:

Breast Cancer With a Poor Prognosis Diagnosed After Screening Mammography With Negative Results

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