New lung cancer test predicts survival
How the Molecular Assay Predicts Lung Cancer Survival
The molecular assay is based on technology developed originally at UCSF. The assay itself was developed by Pinpoint Genomics, a company based in Mountain View, California, and relies on a standard laboratory technique known as quantitative polymerase chain reaction (qPCR).
The analysis begins with a piece of the patient’s cancerous tissue embedded in paraffin wax—the standard way of preserving all tissue samples removed during surgery. Material known as RNA, which reveals the relative activity level of genes within tissues, is then extracted from the tumors. The activity levels of 14 specific genes are then determined and compared to levels in normal lung. Eleven of these genes are linked to lung cancer biology, and the other three are common genes that are used to standardize the measurement of the cancer genes.
Stages of lung cancer
Stage I. Cancer is limited to the lung and hasn’t spread to the lymph nodes. The tumor is generally smaller than 2 inches (5 centimeters) across.
Stage II. The tumor at this stage may have grown larger than 2 inches, or it may be a smaller tumor that involves nearby structures, such as the chest wall, the diaphragm or the lining around the lungs (pleura). Cancer may also have spread to the nearby lymph nodes.
Stage III. The tumor at this stage may have grown very large and invaded other organs near the lungs. Or this stage may indicate a smaller tumor accompanied by cancer cells in lymph nodes farther away from the lungs.
Stage IV. Cancer has spread beyond the affected lung to the other lung or to distant areas of the body.
Small cell lung cancer is sometimes described as being limited or extensive. Limited indicates cancer is limited to one lung. Extensive indicates cancer has spread beyond the one lung.
Pinpoint Genomics developed an algorithm for calculating risk of death after examining tissue taken from 361 patients at UCSF Medical Center who all had surgery to treat a common type of lung cancer called non-squamous, non-small cell lung cancer. The algorithm correlated the levels of these 14 genes with the clinical outcomes of these patients, the theory being that a molecular profile associated with a low, intermediate, or high risk of death in one patient could be used to predict a low, intermediate, or high risk in another patient.
To test their algorithm, the UCSF team partnered with Kaiser Permanente’s Division of Research in Oakland, CA and blindly examined lung samples taken from 433 other patients in northern California with the earliest stage of the same type of cancer. They also used a similar blinded approach to test the algorithm using tissue samples from 1,006 lung cancer patients in China, where lung cancer is one of the leading causes of death. No other clinical trial examining molecular prognostic indicators has ever demonstrated the same result in two different populations with different genetic make-ups on two continents, the team said.
The scientists found that the algorithm very accurately differentiated patients with high, intermediate or low risks of death in these larger cohorts of patients, even for patients with stage II and stage III lung cancer.
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More information: “International, Large-Scale Validation of a Practical Molecular Assay Prognostic of Survival in Resected Non-Squamous, Non-Small Cell Lung Cancer”.
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Provided by University of California, San Francisco