(ChemotherapyAdvisor) – Using a semiannual interval is preferable for ipsilateral mammographic surveillance for breast cancer, according to a team of US-based researchers. This conclusion is based on “Benefit of Semiannual Ipsilateral Mammographic Surveillance Following Breast Conservation Therapy,” which was published in the August issue of Radiology.

This study recruited patients with breast cancer who have had previous breast conservation therapy (BCT). The investigators aimed to make the comparison between recurrence outcomes in 2 groups of women: Compliant with semiannual mammographic surveillance vs noncompliant with an annual ipsilateral mammographic surveillance post-BCT.

In this retrospective review and analysis of post-BCT examinations (1997-2008), the investigators were able to classify the groups of women according to their compliance with an institutional post-BCT protocol, which recommends semiannual mammographic examinations of the ipsilateral breast for 5 years. In terms of classification, a compliant semiannual examination was defined as an examination with an interval of 0–9 months; the noncompliant annual examination interval was 9–18 months. “Cancer recurrence outcomes were compared on the basis of the last examination interval leading to diagnosis,” the investigators wrote.

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The investigators found that, after excluding the initial mammographic follow-up, 8,234 women underwent mammographic examinations, of which 7,169 were semiannual (94 recurrences detected) and 1,065 examinations were annual (15 recurrences detected). Upon statistical analysis of both groups, women that recurred in the semiannual group were diagnosed with an earlier stage of breast cancer than those identified at annual intervals (stage I vs stage II, P=.04; stage 0 + stage I vs stage II, P=.03).

Based on these data, the investigators suggest that “a semiannual interval is preferable for ipsilateral mammographic surveillance, allowing detection of a significantly higher proportion of cancer recurrences at an earlier stage than noncompliant annual surveillance.”