ROLE OF PET/CT IN ASSESSMENT OF POST OPERATIVE COLORECTAL CANCER

Abstract

Colorectal cancer is the third leading cause of cancer worldwide and recurrence of colorectal cancer occurs in about one-third of patients within the first 2 years after surgery and resection of isolated metastases is associated with survival improvement while multifocal metastatic lesions are associated with less favorable prognosis.

Early detection of recurrent colorectal carcinoma has become more important in the past decade, as the treatment options for localized disease have improved significantly; therefore detection of tumor sites throughout the body is needed with high sensitivity and specificity.

Preoperative chemoradiotherapy is increasingly used in patients with colorectal carcinoma and assessment of the therapeutic response is fundamental in order to change an ineffective but possibly toxic chemotherapy protocol or to decide surgical resection.

Most radiologic procedures map the anatomy and morphology of tumors with little or no information about their metabolism. In recent years, imaging with positron emission tomography (PET) for tumor staging and therapy control has been introduced. Rather than anatomic information, it provides physiologic information on glucose uptake and metabolism. The main drawback of PET in tumor imaging is the virtually complete absence of anatomic landmarks, which impedes precise localization of lesions. The major advantage of PET/CT is that both metabolic and anatomic information for the same body region are obtained at nearly the same time. Combined PET/CT facilitates the separation of normal physiologic uptake from pathologic uptake, provides accurate localization of functional abnormalities and reduces the incidence of false-positive and false-negative imaging studies. Our data and in agreement with the previous studies has demonstrated that PET/CT is the technique of choice and indispensible tool for patients with colorectal cancer used in: