In This Section
Cancer
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 and Cancer
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:
- assess the characteristics of the main tumor
- decide if the cancer has spread elsewehere in the body
- select the best treatment based on the unique biology of both the patient and the tumor
- evaluate the patient’s repsonse to treatment
- decide to change treatment based on worsening biology of the tumor
- identify a cancer recurrence early.
How Does Molecular Imaging Help People with Cancer?
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.
- PET, often used in conjunction with computed tomography (CT), is used to diagnose and determine the stage of many types of cancer, including lung, head and neck, colorectal, esophageal, lymphoma, melanoma, breast, thyroid, cervical, pancreatic and brain cancers. It is also used to stage and re-stage common cancers such as lymphoma, lung, breast, prostate and colorectal cancers.
- PET/CT is a useful tool for managing cancer that has metastasized.
Treatment planning
Molecular imaging provides information for better decision-making with regard to chemotherapy, surgery and radiotherapy.
- FDG-PET/CT is becoming an integral part of the initial work-up in patients scheduled to undergo radiation therapy.
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
- PET is a powerful tool for diagnosing and determining the stage of many types of cancer, including lung, head and neck, colorectal, esophageal, lymphoma, melanoma, breast, thyroid, cervical, pancreatic and brain cancers. The value of PET for many other cancers is currently being investigated through the National Oncologic PET Registry.
- By detecting whether lesions are benign or malignant, PET scans may eliminate the need for surgical biopsy or identify the optimal biopsy location
- PET scans help physicians choose the most appropriate treatment plan and assess whether chemotherapy or other treatments are working as intended
- PET scans are currently the most effective means of detecting a recurrence of cancer.
The Future of Molecular Cancer Care
In addition to FDG, the gold standard for PET imaging agents, new radiotracers are being tested that target biomarkers of cancer, such as decreased oxygen and blood vessel growth, as well as specific cancer cell features. Researchers hope these radiotracers will significantly impact patients undergoing therapy. Instead of imaging patients before and at the end of cancer treatment, PET imaging with new radiotracers would allow patients to be imaged throughout he treatment process to determine more quickly whether a therapeutic regimen is working.
In addition to PET, other molecular technologies are under development: optical imaging could provide a means of detecting ovarian cancer and malignant skin lesions and an advanced MR technique called spectroscopy may help distinguish malignant from benign breast tissue, eliminating unnecessary biopsies.
By harnessing the field’s ability to detect and hone in on specific cells and cellular activity, molecular imaging is on the forefront of the trend toward personalized cancer treatment. Scientists are working toward providing physicians with the ability to select a therapeutic regimen based on a tumor’s biological properties as well as the unique biologic characteristics of the patient.