Clinical trial results presented at the 2017 Gastrointestinal Cancers Symposium in San Francisco suggest that the use of PET scans to assess a cancers response to initial chemotherapy may provide doctors with useful information to further tailor chemotherapy.
Standard treatment of patients with stage II-III esophageal and gastroesophageal junction (GEJ) cancers includes chemotherapy with radiation (chemoradiation), followed by surgery. Physicians may use several different chemotherapy regimens without knowing which particular chemotherapy will be most effective.
A CT scan uses X-rays to create a three-dimensional picture of the inside of the body. It shows anything abnormal, including tumors. A CT scan shows detailed pictures of tissues and organs inside the body. A PET scan shows abnormal activity from the cancer. So, the two scans together provide more information about the cancer. PET scans are routinely used to guide therapy decisions in lymphoma but are only now beginning to be explored for this purpose in other cancers.
In the current study doctors administered chemotherapy before chemoradiation and used PET scans after the initial chemotherapy to assess response to treatment in order to see if the early PET scan can help doctors make quick course corrections to maximize patient benefit from chemotherapy.
A total of 257 patients with stage II-III esophageal and GEJ adenocarcinoma were treated with one of two different chemotherapy regimens: either modified FOLFOX-6 or carboplatin/paclitaxel. A PET scan was repeated in all patients after a couple cycles of chemotherapy. If the PET scan demonstrated that the chemotherapy was working, no change in treatment was made. If the PET scan however demonstrated that the chemotherapy was not effective, the chemotherapy was changed to the other regimen.
Overall, 39 out of 129 patients who started treatment with the modified FOLFOX chemotherapy, and 49 out of 128 patients who started with carboplatin/paclitaxel, switched chemotherapy regimens after the results of the PET scan demonstrated treatment was ineffective.
For patients who switched to the alternative chemotherapy almost 16% achieved a complete disappearance of cancer. This is significantly higher than historical experience. Although improvement in chemotherapy regimens and additional studies are ultimately needed this study suggests that PET scans may be a valuable tool to help oncologists individualize treatment for their patients.
Reference: Goodman, Karyn et al, A randomized phase II trial of PET scan-directed combined modality therapy for esophageal cancer. J Clin Oncol 35, 2017 (suppl 4S; abstract 1)