Expression Levels of Protein Linked to Longer Survival After Mesothelioma Surgery

Scientists found a link between expression levels of a specific protein and survival of people with mesothelioma.

According to research published in the medical journal Cancers, the protein Ki67 may dictate patient life expectancy following aggressive mesothelioma surgery.

 

What is Ki67?

Ki67 is a nuclear protein found in the cell nucleus of proliferating (multiplying) cells. It is not detected in quiescent cells (not proliferating). Therefore, high levels of Ki67 are a sign of a fast-spreading cancer.

Ki67 is a biomarker for several types of cancer, including lung cancer, breast cancer, colon cancer and mesothelioma. Researchers found that high levels of Ki67 (at least 15%) was associated with a shorter mesothelioma survival:

• 7.5 months for high expression
• 19 months for low expression

Expression percentages are the amount of cells in the tumor expressing the protein.

 

Measuring Ki67 Protein Expression in Mesothelioma Tumors

The study, which was conducted at hospitals in Turkey and Austria, measured Ki67 protein expression in the tumor samples of 70 people with pleural mesothelioma. This type of mesothelioma forms in the mesothelial lining of the lungs.

The study then analyzed their response to surgery. The two surgery options for pleural mesothelioma are pleurectomy/decortication (P/D) and extrapleural pneumonectomy (EPP). P/D removes the lining of the lungs along with part or all of the diaphragm and pericardium (sac around the heart), but it leaves both lungs intact. EPP removes the lung most affected by mesothelioma tumors.

The 70 study participants all underwent lung-sparing P/D surgery. Their Ki67 tumor expressions were divided into two groups: low expression (15% of less) and high expression (more than 15%).

The group with low Ki67 expression performed much better in terms of survival:

• 31 months (2 years, 7 months) median overall survival for the low-expression group
• 11 months median overall survival for the high-expression group
• 22% 5-year survival for the low-expression group
• 5% 5-year survival for the high-expression group

A few patients in each group received multimodal mesothelioma treatment – such as chemotherapy or immunotherapy before or after surgery. Using a combination of mesothelioma treatment options improved survival for both groups:

• 48 months (4 years) median overall survival for the low-expression group
• 24 months (2 years) median overall survival for the high-expression group

This data proves that doctors should consider Ki67 expression in tumor cells as a valuable biomarker when determining prognosis treatment benefits for patients. People with high expression of Ki67 may not benefit long-term from lung-sparing mesothelioma surgery, whereas people with low expression often live at least four years following multimodal treatment that incorporates surgery.

Mesothelioma Guide patient advocates can explain the benefits and risks of mesothelioma surgery. If you or a loved one is diagnosed with mesothelioma, contact registered nurse Karen Ritter by email at karen@mesotheliomaguide.com to get her expert advice on surgery, chemotherapy, immunotherapy and more.