Mammographic Parenchymal Patterns and Risk of Breast Cancer at and After a Prevalence Screen in Singaporean Women

Background: The objective of this study was to assess the effect of mammographic parenchymal patterns on risk of breast cancer detected at first screen or in the period following a negative screen.

Methods: The study utilizes a nested case-control design with 132 breast cancer patients detected at first screen (from a total of 29 193 screened) and 42 breast cancer patients detected in the period following the first screen. These patients were matched to 348 screened-negative controls. The mammograms were classified according to Tabar's classification for parenchymal pattern and statistical analysis was done by conditional logistic regression.

Results: The risk of breast cancer for women with Tabar pattern IV was significantly high when compared to the remaining patterns (odds ratio 2.59). Risk factors for Tabar pattern IV coincided largely with established risk factors for breast cancer.

Conclusion: The study confirms the increased risk of breast cancer associated with Tabar pattern IV (approximately Wolfe pattern P2), in an Asian population. This pattern is associated with nulliparity and high educational status and is strongly associated with grade 3 cancers.