Colorectal cancer is the uncontrolled growth of cells in the rectum, colon (the large intestine) and it can also affect the appendix.
Patients who are diagnosed with stage 1 and 2 colorectal cancer (cancers affecting the lining of the intestines – stage 1, and the muscle wall – stage 2) are generally only treated with surgery. Patients are not usually treated with post-operative chemotherapy (adjuvant chemotherapy) unless the cancer has spread to the lymph nodes. However up to 25% of patients with stage 1 or 2 colorectal cancer eventually die from the disease re-occurring (recurrence or relapse). For staging to be diagnosed, a small piece of the lymph node is removed (during a biopsy), this is then stained to look for the presence of cancer cells. If this staining shows no presence of cancer cells the cancer is referred to as node negative and classed as stage 1 or 2. However individual cancer cells can still be present in the lymph nodes and not seen during biopsy.
A second method of looking for the presence of cells in lymph nodes can be used, this is called polymerase chain reaction (PCR). PCR works by amplifying DNA, so proteins that are known to be on or in cancer cells can be made visible.
This paper presents the cumulative results from 39 trials with overall 4,087 patients who had either standard staining of lymph node biopsies or PCR detection to identify the presence of isolated cancer cells. It shows that patients who are diagnosed as having isolated cancer cells in their lymph nodes do have a higher chance of disease recurrence. Therefore these patients have a lower chance of survival. The paper discusses that PCR should become a standard method of detection for lymph node involvement. Patients with a positive PCR, showing lymph node involvement, could then have adjuvant chemotherapy with the aim of destroying the isolated cancer cells.
The use of PCR to detect lymph node involvement is still not common practice due to inconsistent results and lack of clinical evidence for its use. However, the technique is available. You may therefore wish to discuss the use of this diagnostic method with your healthcare provider if you are having tests carried out for lymph node involvement in colorectal cancer.
Published By :
Journal of clinical oncology
Date :
Jan 01, 2012
