The Ki-67 score serves as a marker in cancer diagnostics, providing insights into tumor behavior. It indicates how quickly cancer cells are dividing. This quantification offers information about a tumor’s growth and spread potential.
What Ki-67 Is
Ki-67 is a protein found within the nucleus of actively proliferating cells. It is present in cells undergoing growth, DNA synthesis, and division (G1, S, G2, and M phases). The protein is absent in resting (G0 phase) cells, indicating they are not dividing.
Pathologists identify Ki-67 in tumor samples using immunohistochemistry. This method uses antibodies that bind to the protein, making positive cells visible under a microscope. The score is expressed as a percentage, representing the proportion of cancer cells staining positive for Ki-67, reflecting their proliferative activity.
Interpreting Your Ki-67 Score
Interpreting a Ki-67 score involves understanding what percentages signify about tumor aggressiveness. A low score, often below 10-20% depending on cancer type, indicates a slow-growing tumor with fewer actively dividing cells. Such tumors may progress gradually.
Conversely, a high score, frequently above 20-30%, suggests a more aggressive tumor with rapid cell division. These tumors grow and may spread more quickly. Cut-off points for “low” versus “high” vary between cancer types, such as breast cancer and neuroendocrine tumors, and sometimes within subtypes.
A higher Ki-67 score is generally associated with a more aggressive disease course and a greater risk of recurrence. This percentage provides medical teams with additional information to assess a patient’s tumor characteristics. Understanding these percentages helps inform treatment discussions.
How Ki-67 Guides Cancer Treatment
The Ki-67 score guides cancer treatment strategies, particularly in cancers like breast cancer and neuroendocrine tumors. A high score can indicate a tumor is more likely to respond to chemotherapy. This is because chemotherapy drugs target rapidly dividing cells, making tumors with high proliferative activity more susceptible.
A high score might suggest more intensive treatment to manage a rapidly growing tumor. Conversely, a low score may indicate less aggressive treatments, such as hormone therapy alone in certain breast cancers, could be sufficient. This allows for a more tailored and less burdensome treatment plan.
The Ki-67 score also serves as a prognostic marker, indicating the likely disease course. It can help predict cancer recurrence or overall patient outcome. By integrating this information, doctors refine treatment recommendations, optimizing patient care based on tumor behavior.
Factors to Consider with Ki-67 Results
The Ki-67 score is only one component of a comprehensive cancer diagnosis. It is always evaluated with other tumor characteristics and patient factors. These include tumor grade, size, lymph node spread, and the presence of hormone receptors like estrogen receptor (ER), progesterone receptor (PR), and HER2 status.
Variability in Ki-67 assessment can occur between pathology laboratories due to variations in testing methods or interpretation. A score might differ if analyzed by different facilities. Therefore, the Ki-67 result is not viewed in isolation but as part of a larger clinical picture.
Discussing Ki-67 results with an oncologist is important. These specialists integrate all clinical and pathological information to understand the tumor. This comprehensive assessment allows them to determine the most appropriate and personalized course of action for each patient.