Cancer begins when a cell in the body loses its control mechanisms.
Normally, cells divide as needed and when no longer needed, they die. A tumor occurs when this process is disrupted: cells divide more and die less than they should. A tumor may be benign (or non-cancerous) or malignant (cancerous).
In a malignant tumor, cells grow uncontrollably, divide too quickly, and neglect to die. As the abnormal cancer cells multiply, they also invade adjacent cells and use the lymph system and bloodstream to spread throughout the body. As the cancer grows, it disturbs nearby molecules and the normal balance of the body.
There are more than 100 different cancers that result from the out-of control-growth of abnormal cells. Depending on the type of cancer, the disease is treated with surgery, radiation, chemotherapy, hormone therapy, biological therapy and targeted therapy.
According to the American Cancer Society, approximately 1.59 million new cancer cases will be diagnosed and nearly 572,000 Americans will die from the disease in 2011. Cancer causes one in every four deaths in the United States. It is estimated that half of all men and one-third of all women in the United States will develop cancer during their lifetimes.
Fortunately, cancer death rates are dropping (by about one percent annually since 1991) and five-year survival rates also have increased to 66 percent, up from 50 percent in 1975. Both statistics reflect improvements in early detection and treatment.
Molecular imaging has become part of standard care for many types of cancer. By allowing scientists and physicians to see what is happening in the body at a cellular level, molecular imaging provides unique information to assist in the detection, diagnosis, evaluation, treatment and management of cancer. Molecular imaging is also increasingly being used for therapy, providing a means of target-specific drug delivery.
Lymphoma and esophageal, colon and lung cancer are just a few of the many types of cancer in which molecular imaging can truly change the direction and outcome of patient care. The ability of molecular imaging to detect abnormalities very early in the progression of disease has the potential to change medicine from reactive to proactive, detecting and curing disease in its most treatable phase and saving countless lives.
As a tool for evaluating and managing the care of cancer patients, molecular imaging studies help physicians:
In the last 20 years, molecular imaging–primarily through PET with the radiotracer FDG–has become an important part of cancer care, specifically in staging and determining the extent of the disease and identifying a patient’s response to treatment as well as cancer recurrence.
Today, molecular imaging and nuclear medicine are playing even larger roles in the detection, diagnosis and treatment of cancer–and new technologies are continually under development.
Currently, the most frequently used molecular technologies for cancer include positron emission tomography (PET) scans and combination PET and computed tomography (PET/CT) scans, as well as molecular radiotherapy.
PET and PET/CT are used for:
Diagnosis, staging and re-staging
Molecular imaging helps determine the location, extent and metabolic activity of the disease.
Molecular imaging provides information for better decision-making with regard to chemotherapy, surgery and radiotherapy.
Predicting Outcome & Monitoring Treatment Response
PET scans provide an early and accurate way to determine if cancer is responding to treatment. In addition to enabling changes in patient management to be made in real time, it also helps predict treatment response before therapy is initiated.
Advantages of PET
Coronal PET/CT (I), axial PET (II), CT (III), and PET/CT (IV) images of a patient with locally advanced adenocarcinoma of the esophagogastric junction (arrow) before (A) and 14 days after beginning (B) neoadjuvant chemotherapy. Fourteen days after initiation of neoadjuvant chemotherapy, tumor metabolic activity is marginally decreased (<35%). After completion of chemotherapy, more than 50% tumor cells were found in resected specimen.