Researchers at Northwestern University and NorthShore University HealthSystem (both in Evanston, IL) have developed an approach that combines microscopy and spectroscopy to detect the early presence of ovarian cancer in humans. Their screening approach is the first of its kind to examine cells brushed from the neighboring cervix or uterus, rather than the ovaries themselves.
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The research team conducted an ovarian cancer clinical study at NorthShore. Using partial wave spectroscopic (PWS) microscopy, they saw diagnostic changes in cells taken from the cervix or uterus of patients with ovarian cancer even though the cells looked normal under a microscope.
The results have the potential to translate into a minimally invasive early detection method using cells collected by a swab, exactly like a Pap smear. No reliable early detection method for ovarian cancer currently exists.
In previous Northwestern-NorthShore studies, the PWS technique has shown promising results in the early detection of colon, pancreatic, and lung cancers using cells from neighboring organs. If commercialized, PWS could be in clinical use for one or more cancers in approximately five years.
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PWS uses light scattering to examine the architecture of cells at the nanoscale and can detect profound changes that are the earliest known signs of carcinogenesis. These changes can be seen in cells far from the tumor site or even before a tumor forms.
âWe were surprised to discover we could see diagnostic changes in cells taken from the endocervix in patients who had ovarian cancer,â says Vadim Backman, who developed PWS at Northwestern. âThe advantage of nanocytology--and why we are so excited about it--is we donât need to wait for a tumor to develop to detect cancer.â
Backman is a professor of biomedical engineering at the McCormick School of Engineering and Applied Science. He and his longtime collaborator, Hemant K. Roy, MD, formerly of NorthShore, have been working together for more than a decade and conducting clinical trials of PWS at NorthShore for four years. Backman and Roy both are authors of the paper.
âThe changes we have seen in cells have been identical, no matter which organ we are studying,â Backman says. âWe have stumbled upon a universal cell physiology that can help us detect difficult cancers early. If the changes are so universal, they must be very important.â
The study included a total of 26 individuals. For cells taken from the endometrium (part of the uterus), there were 26 patients (11 with ovarian cancer and 15 controls); for cells taken from the endocervix, there were 23 patients (10 with ovarian cancer and 13 controls). The small size of the study reflects the difficulty in recruiting ovarian cancer patients.
Cells were placed on slides and then examined using PWS. The results showed a significant increase in the disorder of the nanoarchitecture of epithelial cells obtained from cancer patients compared to controls for both the endometrium and endocervix studies.
The cells for the ovarian cancer study were taken from the cervix and uterus. For the earlier lung cancer study, cells were brushed from the cheek. For the colon, cells came from the rectum, and for the pancreas, cells came from the duodenum. Cells from these neighboring organs showed changes at the nanoscale when cancer was present.
PWS can detect cell features as small as 20 nm, uncovering differences in cells that appear normal using standard microscopy techniques. PWS measures the disorder strength of the nanoscale organization of the cell, which is a strong marker for the presence of cancer in the organ or in a nearby organ.
The PWS-based test makes use of the âfield effect,â a biological phenomenon in which cells located some distance from the malignant or pre-malignant tumor undergo molecular and other changes.
Full details of the research team's work appear in the International Journal of Cancer; for more information, please visit http://onlinelibrary.wiley.com/doi/10.1002/ijc.28122/abstract or www.northshore.org.
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