Infrared spectroscopy of plasma identified a protein fingerprint that had roughly 90% sensitivity and 80% specificity for detecting breast cancer in a cohort that included women with the disease, women with benign breast conditions, and healthy women (BMC Cancer. 2015;15:408). And a pair of proteins in serum—HSP27 and 14-3-3 sigma—accurately distinguished breast cancer cases from controls in a Chinese population (Proteomics. 2003;3:433-9).
One study has suggested how proteomic biomarkers might be integrated with conventional modalities, showing that a five-protein signature in serum (dtectDx Breast, Provista) performed well among women younger than age 50 years for differentiating benign breast lesions from invasive breast cancer in those with a BI-RADS 3 or 4 mammogram (J Clin Oncol. 2014;32(26 Suppl 20). However, the signature had a fairly high false-positive rate, Dr. Neuhausen noted.
As for yet other types of biomarkers, a panel of circulating cell-free methylated DNA of eight tumor suppressor genes was found to have sensitivity and specificity exceeding 90% for differentiating between samples from breast cancer patients and from unaffected women (PLoS One. 2011;6:e16080).MicroRNA profiles of breast cancer have been identified, but findings have generally been inconsistent across studies (Breast Cancer. 2015;7:59-79). Somatic mutations in p53 and PI3KCA, present in about a third of breast cancers, currently have issues when applied to screening. “Those kinds of things are maybe better for determining response to treatment and that kind of thing. Are they ready for early detection? Not really,” Dr. Neuhausen said.
The situation is similar for DNA copy number, although intriguingly, a recent study of a prenatal test looking for fetal copy number aberrations in maternal plasma incidentally discovered maternal cell-free DNA that had copy number changes (JAMA Oncol. 2015 June 5.doi: 10.1001/jamaoncol.2015.1883). Imaging ultimately found various cancers in three women out of about 4,000 tested.
Dr. Neuhausen disclosed that she had no relevant conflicts of interest.