Clinical value of contralateral breast cancers detected by pre-operative MRI in patients diagnosed with DCIS: a population-based cohort study

OBJECTIVES

For patients with ductal carcinoma in situ (DCIS), data about the impact of breast MRI at primary diagnosis on the incidence and characteristics of contralateral breast cancers are scarce.

METHODS

We selected all 8486 women diagnosed with primary DCIS in the Netherlands in 2011-2015 from the Netherlands Cancer Registry. The synchronous and metachronous detection of contralateral DCIS (cDCIS) and contralateral invasive breast cancer (cIBC) was assessed for patients who received an MRI upon diagnosis (MRI group) and for an age-matched control group without MRI.

RESULTS

Nineteen percent of patients received an MRI, of which 0.8% was diagnosed with synchronous cDCIS and 1.3% with synchronous cIBC not found by mammography. The 5-year cumulative incidence of synchronous plus metachronous cDCIS was higher for the MRI versus age-matched control group (2.0% versus 0.9%, p = 0.02) and similar for cIBC (3.5% versus 2.3%, p = 0.17). The increased incidence of cDCIS was observed in patients aged < 50 years (sHR = 4.22, 95% CI: 1.19-14.99), but not in patients aged 50-74 years (sHR = 0.89, 95% CI: 0.41-1.93).

CONCLUSIONS

MRI at primary DCIS diagnosis detected additional synchronous cDCIS and cIBC, and was associated with a higher rate of metachronous cDCIS without decreasing the rate of metachronous cIBC. This finding was most evident in younger patients.

KEY POINTS

• Magnetic resonance imaging at primary diagnosis of ductal carcinoma in situ detected an additional synchronous breast lesion in 2.1% of patients. • In patients aged younger than 50 years, the use of pre-operative MRI was associated with a fourfold increase in the incidence of a second contralateral DCIS without decreasing the incidence of metachronous invasive breast cancers up to 5 years after diagnosis. • In patients aged over 50 years, the use of pre-operative MRI did not result in a difference in the incidence of a second contralateral DCIS or metachronous invasive breast cancer.

Preoperative breast magnetic resonance imaging and contralateral breast cancer occurrence among older women with ductal carcinoma in situ

Although preoperative magnetic resonance imaging (MRI) can detect mammographically occult contralateral breast cancers (CBCs) among women with ductal carcinoma in situ (DCIS), the impact of MRI on the incidence of subsequent CBC events is unclear. We examined whether MRI use decreases CBC occurrences and detection of invasive disease among women who develop a CBC. Utilizing the Surveillance, Epidemiology, and End Results-Medicare dataset, we assessed overall, synchronous (<6 months after primary cancer diagnosis), and subsequent (≥6 months after diagnosis, i.e., metachronous) CBC occurrence in women aged 67-94 years diagnosed with DCIS during 2004-2009, with follow-up through 2011. We applied a matched propensity score approach to compare the stage-specific incidence rate of CBC according to MRI use. Our sample consisted of 9166 beneficiaries, 1258 (13.7 %) of whom received preoperative MRI. After propensity score matching, preoperative MRI use was significantly associated with a higher synchronous CBC detection rate (108.6 vs. 29.7 per 1000 person-years; hazard ratio [HR] = 3.65; p < .001) with no significant differences in subsequent CBC rate (6.7 vs. 6.8 per 1000 person-years; HR = 0.90; p = .71). The 6-year cumulative incidence of any CBC (in situ plus invasive) remained significantly higher among women undergoing MRI, compared with those not undergoing MRI (9 vs. 4 %, p < .001). Women undergoing MRI also had a higher incidence of invasive CBC (4 vs. 3 %, p = .04). MRI use resulted in an increased detection of synchronous CBC but did not prevent subsequent CBC occurrence, suggesting that many of the undetected CBC lesions may not become clinically evident.

Multicentric and contralateral invasive tumors identified with pre-op MRI in patients newly diagnosed with ductal carcinoma in situ of the breast

Preoperative breast MRI in newly diagnosed cancer patients has several potential benefits. Improved survival for patients with invasive disease as the index lesion is unlikely to be one of these benefits, given what is known from variations in locoregional management in the historic conservation trials. However, this may not be the case for patients with ductal carcinoma in situ (DCIS), as the discovery of unsuspected invasive cancer located elsewhere from the biopsy-proven DCIS could result in decreased survival if left undetected and untreated. In support of this hypothesis, a previous observational study of a large cohort of DCIS patients revealed the development of invasive cancer to be the most common event after unilateral DCIS treatment, occurring in 3.9%, mostly in the opposite breast. These cancers appeared on mammography or clinical exam within a short time frame (median 2.9 years) and were associated with a diminution in survival. Given these second events occurring so soon after DCIS treatment, it must be considered that invasive cancers were present elsewhere, but mammographically occult, at the time of DCIS diagnosis. To examine this possibility, 288 consecutive patients with newly diagnosed DCIS underwent preoperative MRI, with the discovery of separate foci of invasive cancer, either multicentric or contralateral, occurring in 3.5% of patients, a similar incidence to the short-term observational study. These "elsewhere" invasive cancers are presented here with details of pathology such that both Stage I and Stage II disease can be seen as clinically significant, with the usual stage-based survival implications.

Comparison of whole genome amplification methods for analysis of DNA extracted from microdissected early breast lesions in formalin-fixed paraffin-embedded tissue

To understand cancer progression, it is desirable to study the earliest stages of its development, which are often microscopic lesions. Array comparative genomic hybridization (aCGH) is a valuable high-throughput molecular approach for discovering DNA copy number changes; however, it requires a relatively large amount of DNA, which is difficult to obtain from microdissected lesions. Whole genome amplification (WGA) methods were developed to increase DNA quantity; however their reproducibility, fidelity, and suitability for formalin-fixed paraffin-embedded (FFPE) samples are questioned. Using aCGH analysis, we compared two widely used approaches for WGA: single cell comparative genomic hybridization protocol (SCOMP) and degenerate oligonucleotide primed PCR (DOP-PCR). Cancer cell line and microdissected FFPE breast cancer DNA samples were amplified by the two WGA methods and subjected to aCGH. The genomic profiles of amplified DNA were compared with those of non-amplified controls by four analytic methods and validated by quantitative PCR (Q-PCR). We found that SCOMP-amplified samples had close similarity to non-amplified controls with concordance rates close to those of reference tests, while DOP-amplified samples had a statistically significant amount of changes. SCOMP is able to amplify small amounts of DNA extracted from FFPE samples and provides quality of aCGH data similar to non-amplified samples.