Yet another study is illustrating the perils of missing mammography screening. New research in JAMA Network Open found that women diagnosed with breast cancer who missed their previous screening exam had signs of delayed diagnosis and worse clinical outcomes.
Mammography screening is generally credited – along with improved treatments – with a steady decline in breast cancer death rates since the start of population-based breast screening.
- But most studies on mammography’s effectiveness tend to compare women who participated regularly in screening with those who never did.
That’s not really a realistic comparison these days, as mammography’s relatively high compliance rate means that most women are getting screened at least some of the time.
- But what happens if women miss a screening exam? In a BMJ study published last month, researchers found that women who missed their first screening exam had a 40% higher risk of breast cancer death.
In the current study, researchers took a slightly different tack, looking at 8.6k women in Sweden whose breast cancer was detected on screening exams starting in 2015.
- In all, 17% of women missed the screening exam immediately before their cancer diagnosis.
Compared to women who attended all screening rounds, those who missed their previous exam had higher adjusted odds ratio for…
- Larger tumors ≥ 20 mm (AOR = 1.55).
- Lymph node involvement (AOR = 1.28).
- Distant metastasis (AOR = 4.64).
- Worse breast cancer-specific survival (AOR = 1.33).
- Lower 20-year breast cancer-specific survival (86% vs. 89%).
What’s more, the program’s cancer detection rate per 1k screenings was sharply higher in the second screening round for women who missed the first round (7.35 vs. 5.59).
- This is most likely a sign that cancers that could have been detected in the first round instead were detected in the second round – another sign of delayed diagnosis.
Women who had missed their previous screening tended to be younger, unemployed, unmarried, and born outside of Sweden, and also had lower income.
- Women with these characteristics could be targeted for more intensive outreach, such as shorter invitation intervals or outreach after a missed appointment.
The Takeaway
The new study once again highlights the importance of regular mammography screening in detecting breast cancer. Even one missed exam can have serious clinical consequences – highlighting the importance of identifying and contacting women who might be more prone to missed appointments.
