The study reviewed here suggests that an experimental, non-invasive way to assess suspicious areas in the breast -- called optical tomography -- may be able to help determine if an area is cancer or not. The suspicious areas were first identified by mammogram or breast ultrasound.
Screening mammograms save lives by finding breast cancer early, when it's most easily treated. Still, mammograms aren't perfect. They sometimes identify an abnormal area that looks like cancer, but turns out to be normal. Doctors call this false alarm a false positive. Besides the fear of a breast cancer diagnosis, a false positive usually means more tests (including biopsies) and follow-up doctor visits. The process can be very stressful and upsetting.
Sometimes when a mammogram finds a suspicious area, a breast ultrasound is done to help figure out if the area is cancer or not. But as with mammograms, ultrasounds also can have false positive results. If both a mammogram and a breast ultrasound suggest that an area is cancer, a biopsy (an invasive procedure) is usually done to make a final decision on whether the area is cancer or not.
Having a more reliable, non-invasive way to figure out if a suspicious area is breast cancer or not could help women avoid unnecessary biopsies and the stress associated with false positives.
Hemoglobin is the part of a red blood cell that carries oxygen to tissue in the body. If there is a lot of blood in tissue, the amount of hemoglobin in the tissue will high. Breast cancers typically need more oxygen and nutrients compared to healthy tissue. So a suspicious area that is cancer is likely to have more blood flowing through it and so higher amounts of hemoglobin.
But hemoglobin in a cancer will have less oxygen attached to it because cancers tend to use more oxygen than healthy tissue. Optical tomography is an imaging test that aims a beam of infrared light on the suspicious area through the skin. Optical tomography is guided by ultrasound. The infrared light is not radiation and doesn't harm the skin or other tissues. The amount of light reflected back from the suspicious area is based on the amount of hemoglobin in the area and how much oxygen the hemoglobin has attached to it. Compared to areas that aren't cancer, breast cancers have more hemoglobin with less oxygen in them.
In this study, 178 women had a breast biopsy because of a suspicious area in the breast that was found by a mammogram or a breast ultrasound. Before biopsy, all the women also had optical tomography of the suspicious area. The results suggest that optical tomography was an effective way to decide if an area was cancer or not, especially if the suspicious area is small.
For smaller suspicious areas:
For larger suspicious areas:
Optical tomography also may be able to help monitor how well advanced-stage breast cancers respond to treatment.
While these results offer promise, much more research is needed before doctors know how optical tomography can best be used to evaluate suspicious breast areas found by a mammogram or a breast ultrasound.
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(MedPage Today) -- The hemoglobin content of breast masses as measured by optical tomography accurately distinguished malignant from benign lesions, suggesting the technique's potential as an adjunct to mammography, according to clinical study data.
Researchers used the still-investigational imaging modality to assess breast lesions in 178 women and found that malignant lesions had significantly higher hemoglobin values, consistent with tumor angiogenesis (P<0.001). The sensitivity and specificity for in-situ and T1 lesions exceeded 90%, with values only marginally reduced for more advanced tumors, said Quing Zhu, PhD, of the University of Connecticut in Storrs, and colleagues.
"Optical tomography has tremendous potential to provide clinically useful functional information about tumor angiogenesis and tumor hypoxia," Zhu and co-authors reported in an article published online in the journal Radiology.
"We showed that intrinsic total hemoglobin contrast holds promise as an adjunct to diagnostic mammography and ultrasound for distinguishing early-stage invasive breast cancers from benign lesions," they added. "The total hemoglobin contrast may also help to distinguish some high-risk proliferative lesions from nonproliferative lesions."
The rationale behind the study was the difficulty in characterizing small breast lesions revealed as a result of the increased use of screening mammography.
To help characterize these lesions, breast ultrasound often is used as an adjunct to mammography, but overlap in some features of malignant and benign breast lesions can complicate ultrasound diagnosis, leading to biopsies that prove benign in 70% to 80% of cases, the authors noted.
Diffuse optical tomography in the near-infrared region has demonstrated potential for clinical applications in oncology. The imaging modality quantifies tumor hemoglobin content, which correlates with tumor angiogenesis and hypoxia, the authors explained.
In a preliminary clinical evaluation, ultrasound-guided optical tomography showed that early-stage invasive breast tumors had a twofold greater concentration of total hemoglobin compared with benign lesions (Neoplasia 2003; 5: 379-388, Radiology 2005; 237: 57-66). Zhu and colleagues continued the evaluation of optical tomography as a means of distinguishing malignant and benign breast lesions.
Their study involved 178 consecutive women (mean age 52) who underwent ultrasound-guided breast biopsies at the University of Connecticut
Health Center in Farmington and at Hartford Hospital. Each procedure included imaging with a hand-held probe consisting of a co-registered ultrasound transducer and a near-infrared imager.
Light absorption was measured at two optical wavelengths, and lesion angiogenesis was calculated from total hemoglobin concentration and compared with biopsy results. Women found to have malignant lesions underwent excision, and total hemoglobin was compared with pathologic parameters.
The results showed two in situ carcinomas, 35 T1 cancers, 24 T2-T4, and 114 benign lesions. The in situ and T1 lesions had mean and mean maximal total hemoglobin values of 71.9 and 102.0 µmol/L, respectively. The T2-T4 lesions had mean and mean maximal concentrations of 67.0 and 100.3 µmol/L, respectively. Corresponding values for benign lesions were 39.1 and 55.1 µmol/L.
The mean and mean maximal total hemoglobin concentrations were significantly higher in the malignant lesions than in the benign lesions (P<0.001).
Total hemoglobin concentration had a sensitivity, specificity, positive predictive value, and negative predictive value of 92%, 93%, 81%, and 97%, respectively, for in-situ and T1 cancers and corresponding values of 75%, 93%, 69%, and 95% for T2-T4 tumors.
"Our technique is best suited to characterizing ultrasound-visible lesions, and it may prove to be value in investigating lesions that are small and considered indeterminate on the basis of mammographic and ultrasound results," the authors wrote. "When our technique is used as an adjunct to mammography and ultrasound in screening, the additional tumor angiogenesis information may yield a more accurate preoperative diagnosis.
"For large ultrasound-visible lesions, this technique can provide some total hemoglobin distribution features, such as heterogeneous peripheral enhancement and/or posterior shadowing, that can add diagnostic value to ultrasound," Zhu and colleagues wrote. "In addition, the total hemoglobin distribution can be monitored and used to assess response in patients who have locally advanced cancers and who are undergoing neoadjuvant chemotherapy."
The study was supported by the National Institutes of Health
Zhu and coauthors said they had no financial disclosures.
Primary source: Radiology Source reference: Zhu Q et al. "Early-stage invasive breast cancers: Potential role of optical tomography with US localization in assisting diagnosis" Radiology 2010; DOI: 10.1148/radiol.10091237.
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