Can cyclin D1 levels predict survival in colorectal cancer?

The authors evaluated the association between cyclin D1 level, overall survival and disease-free survival in colorectal cancer patients.

In recent years, much attention has been focused on the involvement of cyclin D1 in tumor development and progression. Cyclin D1 is a protein that regulates the cell cycle, or the growth and division of cells. Expression of this protein has been observed to be abnormally high in one third or more of colorectal cancers. Many studies, therefore have evaluated whether cyclin D1 over-expression is a prognostic factor (indicating the outcome of the disease) for survival in patients with colorectal cancer.

The authors included a total of 22 previously published studies (including a total of 4150 patients) in their analysis. 

Based on data derived from 21 of these studies, high cyclin D1 levels were associated with 27% reduced likelihood of overall survival compared to low cyclin D1 levels. High cyclin D1 levels were associated with 44% reduced likelihood of overall survival in Asian populations, and 17% reduced likelihood in non-Asian populations.

In those treated with surgery alone, high cyclin D1 levels were associated with 23% reduced likelihood of survival, and 33% reduced likelihood of survival in those treated with surgery and chemoradiation (chemotherapy plus radiation therapy).

Based on data derived from 10 studies, high cyclin D1 levels were associated with 40% reduced likelihood of disease-free survival (survival without any signs or symptoms of the treated cancer). High cyclin D1 levels were associated with 59% reduced likelihood of disease-free survival in Asian populations, and 33% reduced likelihood in non-Asian populations.

In those treated with surgery alone, high cyclin D1 levels were associated with 31% reduced likelihood of disease-free survival, and 67% reduced likelihood of disease-free survival in those treated with surgery and chemoradiation.

Patients above 60 years of age had significantly higher cyclin D1 levels than patients under 60 years of age. Those with high cyclin D1 levels were 36% less likely to have a tumor under 5 cm in size, 25% less likely to have negative lymph nodes (no cancer cells found in the lymph nodes) and 40% less likely to have distant metastasis (spread of the cancer to other organs). 

The authors concluded that a high level of cyclin D1 was an unfavourable prognostic factor for colorectal cancer.

The data used to compile the results was retrospective (collected from studies performed in the past). The length of follow-up varied between the studies included in the analysis and the methods used to measure cyclin D1 levels also had different sensitivities.