Posts Tagged ‘college’

New method for non-invasive prostate cancer screening

Now a team of researchers led by Shaoxin Li at Guangdong Medical College in China has demonstrated the potential of a new, non-invasive method to screen for prostate cancer, a common type of cancer in men worldwide. They describe their laboratory success testing an existing spectroscopy technique called surface-enhanced Raman scattering (SERS) with a new, sophisticated analysis technique called support vector machine (SVM).

As they described in a new paper in Applied Physics Letters, from AIP Publishing, they combined SERS and SVM and applied them to blood samples collected from 68 healthy volunteers and 93 people who were clinically confirmed to have prostate cancer. They found their technique could identify the cases of cancer with an accuracy of 98.1 percent.

If the technique proves safe and effective in clinical trials, it may become a new method available to patients and their doctors, helping to improve the early detection and diagnosis of this type of cancer, said Li.

“The results demonstrate that label-free serum SERS analysis combined with SVM diagnostic algorithm has great potential for non-invasive prostate cancer screening,” said Li. “Compared to traditional screening methods, this method has the advantages of being non-invasive, highly sensitive and very simple for prostate cancer screening.”

A COMMON CAUSE OF CANCER

According to the World Health Organization, prostate cancer is one of the most common types of cancer in men worldwide and a leading cause of cancer-related death. Every year, there are about 899,000 new cases and 260,000 mortalities, comprising 6 percent of all cancer deaths globally. About 1 in every 6 men will develop prostate cancer over their lifetimes.

While a simple blood test for elevated levels of a protein marker known as prostate specific antigen (PSA) has been used for years to screen for early cases of prostate cancer, the test is far from perfect because the elevated PSA levels can be caused by many things unrelated to cancer. This contributes to over-diagnosis, uncomfortable tissue biopsies and other unnecessary treatment, which can be costly and carry significant side effects. Because of this, the U.S. Preventative Services Task Force now recommends against PSA-based screening for prostate cancer.

According to Li, many scientists have thought about applying SERS to cancer detection because the surface-sensitive type of spectroscopy has been around for years and is sensitive enough to identify key molecules in very low abundance, like pesticide residues on a contaminated surface. This would seem to make it perfect for spotting subtle signals of DNA, proteins or fatty molecules that would mark a case of cancer — exactly why he and his team tackled the problem.

The challenge, he said, was that these changes were, if anything, too subtle. The signal differences between the serum samples taken from the 68 healthy volunteers and the 93 people with prostate cancer were too tiny to detect. So to accurately distinguish between these samples, Li’s group employed a powerful spectral data processing algorithm, support vector machine (SVM), which effectively showed the difference.

While the work is preliminary, it shows that serum SERS spectroscopy combined with SVM diagnostic algorithm has the potential to be a new method for non-invasive prostate cancer screening, Li said. The next research step, he added, is to refine the method and explore whether this method can distinguish cancer staging.

source : http://www.sciencedaily.com/releases/2014/09/140902114041.htm

Some women still don’t underststand ‘overdiagnosis’ risk in breast screening

In a survey of around 2,200 women, Cancer Research UK scientists at University College London (UCL) found that 64 per cent felt they fully understood the information given about overdiagnosis — the chance that screening will pick up cancers that would never have gone on to cause any harm — by the National breast screening programme.

Information about overdiagnosis has only been included in the NHS breast screening invitation leaflets since late 2013, meaning that overdiagnosis is likely to be a new concept for many people.

But despite uncertainty over the information they were given, intentions to attend breast screening remained high, with only seven per cent of women saying they would be less likely to attend screening after receiving the overdiagnosis information. On the other hand, four per cent of women said they would be more likely to attend screening after receiving the information.

Study author, Dr Jo Waller, a researcher at the Health Behaviour Research Centre at UCL, said: “While there is clearly room for improvement, the information leaflet does appear to help some women make a decision about whether or not to have breast screening.

“But the study found that many women still struggle to understand the balance of benefits and harms linked to breast screening, so we need to find better ways to communicate the risks as well as the benefits.”

Overdiagnosis happens because some breast cancers grow so slowly that it would take more than a lifetime for them to threaten a woman’s health. For every life that is saved through screening, researchers estimate that around three women will be overdiagnosed with breast cancer, although there is presently no way of telling the difference between life-threatening cancers and cancers that are overdiagnosed, either at diagnosis or after treatment.

Sara Hiom, Cancer Research UK’s director of early diagnosis, said: “We think it’s vitally important for women to have clear information about breast screening, the balance of benefits and harms and the fact that they could be diagnosed with and treated for a cancer that might not have caused them harm.

“We are committed to providing quality information that can help women understand the harms and benefits of breast screening, and research like this can help us refine the information we offer to be sure that it is as helpful and understandable as possible.

“The concept of overdiagnosis is still very new for a lot of women because it has only been included in the NHS leaflets for a year. We hope that over time, people’s understanding of this concept will increase as more and more women receive information explaining this risk of screening.

“Any woman invited for breast screening and worried about the risks of overdiagnosis can speak to our specialist cancer nurses on freephone 0808 800 4040.”

source : http://www.sciencedaily.com/releases/2014/08/140829083906.htm

Sequence of rare kidney cancer reveals unique alterations involving telomerase

The collaboration, a project of the National Institutes of Health’s Cancer Genome Atlas initiative, completed the sequence of chromophobe renal cell carcinoma and published the results today in the journal Cancer Cell.

“The Cancer Genome Atlas is a federally funded national effort that has already completed the sequence of many major types of cancer (breast, lung, ovarian, for example), but this project is now branching out to sequence more rare types of cancer,” said Dr. Chad Creighton, associate professor of medicine and a biostatistician in the NCI-designated Dan L. Duncan Cancer Center at Baylor and the lead and corresponding author on the report. “The idea is that with a better understanding of these more rare types of cancers, we gain new insight that might be relevant to how we study other types of cancer. The findings in this study are a perfect example of that.”

Chromophobe renal cell carcinoma is a rare type of kidney cancer, with approximately 2,000 new cases diagnosed each year in the United States. A majority of patients survive the disease.

Clinical impact

“Although most patients are reassured when the pathology of their kidney tumor comes back as chromophobe, we all have cared for patients who developed and died from metastatic chromophobe kidney cancers,” said Dr. Kimryn Rathmell, associate professor of hematology and oncology in the Lineberger Comprehensive Cancer Center at the University of North Carolina at Chapel Hill and a co-senior author on the study. “This report is incredibly exciting for physicians who care for these patients because all of the treatment plans we have had to this point have been based on the biology of the more common kidney cancer type, as if chromophobe must be a close relative of that disease.”

The project shows with no uncertainty that chromophobe renal cell carcinoma represents a distinct cancer entity, and reveals exciting biology inherent to the disease that we hope in the future will allow new therapies to be developed specifically for the chromophobe type of kidney cancer, Rathmell said.

The team sequenced 66 tumor samples at Baylor’s Human Genome Sequencing Center. Other types of data were collected on these samples and integrated with the sequencing, including gene expression and epigenetic data. In addition to sequencing known genes, DNA from mitochondria and from the entire genome was also sequenced.

Chromosomes

A majority (86 percent) of the samples were missing one copy or a major part of chromosomes 1, 2, 6, 10, 13 and 17. Losses of chromosomes 3, 5, 8, 9, 11, 18 and 21 also were noted with significant frequencies (12 — 58 percent).

Chromosomes are the packaging of our DNA. Normally, each person receives a copy of each of 23 chromosomes from each parent for a total of 46.

When scientists looked for genes that were altered or missing, only two genes, TP53 and PTEN, were identified with a sizable frequency.

Extra step in analysis

The most surprising and significant finding came after the team took an “extra step” with their analysis, Creighton said.

“Instead of just looking specifically at the exome, we also analyzed the entire genome, something not typically done in these genomic studies,” said Creighton. The exome, the part of the genome used to make proteins, constitutes only 1 percent of the total genome, where the other 99 percent is often ignored in studies.

With whole exome analysis, scientists are just looking within the boundaries of known genes, to see which are broken and may have caused the disease, he explained.

“However, when you look outside of the genes, there is much more going on,” said Creighton. “For example, gene regulatory features of the genome can be altered.”

TERT promoter region

From whole genome analysis, the team observed a significant amount of structural rearrangements or breakpoints involving the promoter region of a gene called TERT, which encodes for the most important unit of the telomerase complex.

Telomerase represent the “clock” of the cell, Creighton said. “This plays a critical role in cell division, and with many cancer cells, telomerase levels are really high and time never really runs out, which allows the cell to never die. “

It was the promoter region, not the actual gene, that was affected, Creighton clarified. “Since there isn’t a breakdown in the actual gene, this malfunction is not picked up in whole exome analysis.”

The study also raised intriguing questions about the roles of mitochondrial DNA alterations and of the cell of origin involved in cancer initiation, the authors noted.

This could signify new approaches for how scientists should conduct molecular studies of cancer, he said. “We need to survey the regulatory regions for other cancer types as well.”

Data from all projects of The Cancer Genome Atlas are available for scientists around the world to study. “This effort has had a huge impact on how we study cancer as a whole,” said Creighton.

source : http://www.sciencedaily.com/releases/2014/08/140821124829.htm