Samples

Training set

To discover new biomarkers, 100 colon tumor samples and their 100 normal paired mucosa will be extensively studied . In addition, 50 colon mucosa samples of healthy controls participating in a colorectal cancer screening program will be used as reference.

Patient characteristics:

Stage II colon cases
All the cases included in this project are pathologically diagnosed stage II colon cancer. These patients, without node involvement, usually have good prognosis after radical surgery, but 20% of them will recur. Clinical criteria are poor predictors of recurrence.

Without adjuvant therapy
All patients included in the Colonomics project have not received adjuvant chemotherapy. This will allow us to analyze prognostic factors associated to recurrence.

Stability of microsatellites
Microsatellite unstable tumors have excluded. This are about 8% in Spain, and have better prognosis, but their expression profile and genomic alterations profile are known to be very different from stable tumors.

Follow up
All patients included have at least 3 years of clinical follow up.

Validation series

Three validation studies will be used to sequentially confirm the usefulness of the candidate biomarkers.

  1. Series of cases We already have extracted DNA from the tumor and paired mucosa for more than 400 cases. An additional series of 500 cases has been identified in the Tumor Bank of our hospital and we are in the process DNA extractions from frozen tissue. For the first 300 cases (belonging to a case-control study performed during 1996-98), and for all cases included since 2007 we also have frozen blood (plasma and serum) available.

    In this series we can evaluate the sensitivity of the diagnostic biomarkers (proportion of cases with cancer detected by the biomarker). The clinical data of these cases is available in a database that includes pathological characteristics and treatments received.

  2. Series of clinical screening We have blood, feces and DNA extracted from a series of 410 consecutive unselected patients who underwent a colonoscopy after suspicion of colonic pathology (symptoms). Of these, 210 (54%) were normal, without colonic lesions, 52 (13%) had a benign polyp, 71 (18%) had an adenoma, 14 (4%) had inflammatory bowel disease and 43 (11%) had cancer. Biopsy specimens of the lesions and paired normal mucosa are available and DNA extracted.

    In this series we can evaluate the sensitivity and specificity of the diagnostic biomarkers. Moreover, this series provides blood and feces, which allows us to test if the biomarker is useful in a easily obtainable fluid.

  3. Series of population screeening The series will include healthy individuals who undergo a colonoscopy after a positive FOB test during their participation in the population screening program for colorectal cancer in L’Hospitalet, which coordinates our research team. The objective is to request consent to obtain blood samples and mucosal biopsies of normal mucosa and lesions in a series of at least 500 participants. A sample of 200 patients participating in the population screening program with a negative FOB test will be invited to have a colonoscopy.

    In this series we will test the validity of the biomarkers in a setting similar to that of real practice.

Continue to validation plan ->