More than 12 cancer types were studied in this project, which is a part of The Cancer Genome Atlas

New molecular and genetic knowledge is making it possible for researchers to propose a new system for classifying tumors. Upon implementation, such a system will give oncologists and pathologists, and clinical laboratory professionals a new tool to improve how they diagnose and treat cancer patients.

Tumor categories—defined by cell types instead of where they are found in the body—may lead to more accurate diagnoses and more effective treatments for one in 10 patients, according to the recent study. It was summarized in a Medline Plus Health News By Date story posted on the National Institutes of Health (NIH) website.

Study was Part of the Cancer Genome Atlas Project

The research was part of National Cancer Institute’s The Cancer Genome Atlas (TCGA) project and was funded in part by NIH.

Authors of the study suggested cancers are more likely to be molecularly and genetically similar based on their cell type of origin, as opposed to tissue type of origin, according to a news release issued by the Buck Institute for Research on Aging at the University of California, San Francisco (UCSF).

Pathologists would be affected directly by a molecular system for classifying tumors. Of course, more research is needed before a new system will be accepted for use in clinical settings. But the TCGA scientists’ findings—especially in areas of bladder and breast cancers—are compelling. Eventually, pathologists may need to have comprehensive lists of molecular features that distinguish cancer categories at their fingertips and near their microscopes.

Largest Cancer Genomic Study Reclassifies Tumors

The scientists analyzed DNA, RNA, and protein from 3,527 specimens that represented 12 different cancer types. Their findings, which comprise the largest cancer genomic study to date, were published in a recent edition of the journal Cell.

In this study, about 800 specimens were breast cancers and 120 specimens were bladder cancers. Other cancers involved in the study included brain, colon, endometrial, kidney, and lung tumors. Several different cancer types converged into common subtypes, the authors wrote in Cell.

They found at least 10% of tumors—and possibly as high as 50%—could be identified differently if oncologists determined their diagnoses by a tumor’s molecular make-up, noted an article in the San Francisco Chronicle.

“The old system [of] classifying cancer by the tissue of where it arose [orginated] is outdated. It’s been in existence for over 100 years now, and we know it doesn’t merit the true nature of the cancer,” stated Christopher Benz, M.D., a Professor at the Buck Institute for Research on Aging and co-senior author of the study.

More than 150 scientists from around the U.S. also participated in this study.

christopher-benz-phd

Pictured above is Christopher Benz, M.D., a Professor at the Buck Institute for Research on Aging and co-senior author of a study published in the journal Cell. The study addresses the idea of categorizing tumors based on their molecular make-up, instead of where they originated in the body. It’s part of National Cancer Institute’s The Cancer Genome Atlas Project.  “We’re just appreciating the tip of the iceberg when considering the potential of this multi-platform type of genomic analysis. It could be as many as 30% or 50% of cancers need to be reclassified,” he said in a Buck Institute press release on the study. (Photo copyright by University of California at San Francisco.)

Compelling Findings about Bladder and Breast Cancers

Identification of at least three different subtypes of bladder cancer drew the attention of researchers. One subtype closely resembles a form of non-small cell lung cancer called lung adenocarcinoma.

Another subtype of bladder cancer looked like squamous cell cancers of the head and neck and the lungs, the news release explained.

An analysis of breast cancer tumors surprised researchers: Basal-cell-like cancers of the breast—referred to as triple-negative —are a distinct class of tumor. They have molecular wiring unlike other breast cancers.

“Even though these basal-like cancers arise in the breast, on the molecular level, they have more in common with ovarian cancers and cancers of squamous cell origin than to other subtypes of breast cancer,” said study co-lead author Christina Yau, Ph.D., a staff scientist at the Buck Institute and Assistant Professor of Surgery at UCSF.

Implications for Patient Care if New Cancer Classification is Developed

As to the study’s implications for patient care, Benz said a one-size-fits-all approach to treating cancers of the same tissue of origin may not be as effective as naming based on molecular make-up. Such an approach could be why some people respond poorly to oncology treatments, while others do well, according to a story in the Marin Independent Journal.

“A significant fraction of bladder cancers look more like certain lung cancers and, therefore, should probably best be treated by lung cancer therapies, not just the all-in-one sort of bladder therapy,” Benz told the Marin Independent Journal.

Where to Go From Here?

What are the next steps in the process to essentially rename cancers? One big step is finding the money. About $50,000 to $100,000 may be needed to accurately classify a single tumor’s subtype, reported the Marin Independent Journal.

Experts reportedly foresee challenges associated with having effective treatments ready for new cancer subtypes. Still another step is to sequence more cancers, such as cervical, prostate, liver, and melanoma, noted the San Francisco Chronicle report. The next round of analysis is expected to involve more than 20 different tumor types.

While researchers continue their work on what Benz called a “new oncology textbook,” pathologists and medical laboratory professionals are advised to stay up-to-date on the TCGA’s efforts to advance the molecular basis of cancer.

Indeed, knowledge about the genetic and molecular basis of cancer is growing. And the proposal to create a different tumor classification seems logical. But a reclassification of tumors will not only change the oncology textbook, it also has the propensity to revamp a huge section of pathology’s body of knowledge.

—By Donna Marie Pocius

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