The following article features coverage from the AACR Annual Meeting 2022. Click here to read more of Cancer Therapy Advisor’s conference coverage.

New research has challenged the assumption that recurrence of ductal carcinoma in situ (DCIS) always originates from the initial tumor.

Researchers found that, in 18% of cases, the recurrent tumor was molecularly unrelated to the original tumor.

These findings were presented at the AACR Annual Meeting 2022 by Tanjina Kader, PhD, of Peter MacCallum Cancer Centre in Melbourne, Australia.


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For this study, Dr Kader and colleagues analyzed 67 pairs of matched primary DCIS and ipsilateral recurrence cases to explore their genetic makeup. The researchers also analyzed 32 cases of non-recurrent DCIS.

The team performed DNA sequencing for each case, analyzed the sequencing data, and performed phylogenetic analyses to establish whether the primary DCIS and the recurrent tumors originated from a common ancestor cell.

The results showed that 82% of recurrent cases were clonal, but 18% of apparent recurrences were molecularly unrelated to the original tumor.

The researchers found that the likelihood of clonality was not significantly associated with the grade of primary DCIS (P =.72), estrogen receptor status (P =.74), HER2 status (P =.82), use of radiotherapy (P =.43), or the type of recurrence (DCIS or invasive breast cancer; P =.78). 

The researchers also found evidence to suggest that TP53 mutation and 4 chromosomal changes (5q loss, 17q gain, 11q13.3, and 20q13.2) could predict DCIS recurrence. 

However, these biomarkers were not observed in the non-clonal cases of recurrence. The non-clonal cases had similar genetic profiles as the non-recurrent cases of DCIS.

Based on these findings, Dr Kader recommended that, in cases of an apparent recurrence after a prior DCIS, treating physicians should request paired molecular testing to determine whether the recurrent lesion is related to the original tumor. She noted that a patient with a non-clonal tumor might face a higher risk of subsequent breast cancers.

Read more of Cancer Therapy Advisor’s coverage of AACR 2022 by visiting the conference page.

Reference

Kader, T, Mahale, S, Zethoven, M, et al. Predictive biomarkers of recurrence may not be useful for deescalating treatment of breast ductal carcinoma in situ due to de novo ipsilateral breast carcinoma development. Presented at AACR 2022; April 8-13, 2022. Abstract 43.