During the course of treatment, it is important to know if the treatment is working and chemotherapy treatment monitoring is a strength of PET/CT imaging. Metabolic changes occur before anatomical changes and in general, the greater the decline in radiopharmaceutical uptake, the better the response to treatment and the better the outcome. Physicians utilize PET/CT data to assess response to lung cancer treatments by comparing a baseline PET/CT scan with another one done after one or two cycles of treatment.
After treatment is complete, it is important to know if any active cancer cells remain in the body. Whole-body PET/CT imaging is useful to help the physician detect post treatment residual disease when anatomic imaging is confusing due to distortion from surgery or radiation. Although the tumor mass or scar may be present and visible on CT scans, the cells may no longer be alive and will not absorb the radioactive tracer. Conversely, if the cancer cells have come back in either lymph nodes or scar tissue from surgery, PET/CT can detect the accumulation of the radioactive glucose much sooner than a CT scan can detect the change.
If anything suggests that the cancer might have come back in either the lung or elsewhere, the doctor will want to do more tests. If retreatment by surgery, radiation therapy, or chemotherapy can be started sooner, it can improve the chance of beating the disease.
PET/CT can be used to image lung cancer response to therapy and to help physicians detect recurrence in treated lesions.
Source: Atlas of Clinical Positron Emission Tomography by Sallie F. Barrington, Michael N. Maisey and Richard R. Wahl. Oxford University Press, Inc. New York, NY.