Metabolic imaging predicts neoadjuvant therapy response before pancreatic cancer surgery
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The addition of 18-fluorodeoxyglucose to PET provided significant prognostic benefit in objective assessment of neoadjuvant chemotherapy response among patients with borderline resectable/locally advanced pancreatic cancer.
The findings, published in JNCCN — Journal of the National Comprehensive Cancer Network — may help guide decisions on whether to proceed with complex surgery, continue current treatment or consider a chemotherapy switch, researchers noted.
Methods
Anatomic imaging with CT or MRI poorly predicts response to neoadjuvant therapy among patients with borderline resectable/locally advanced pancreatic ductal adenocarcinoma, and measurement of changes in carbohydrate antigen 19-9 (CA 19-9) markers produces inconsistent results and often is not possible. Although pathologic response highly predicts survival after neoadjuvant therapy, it is only known postoperatively, according to study background.
For this reason, Amro M. Abdelrahman, MBBS, MS, postdoctoral research fellow in the department of surgery at Mayo Clinic, and colleagues sought to evaluate metabolic imaging with preoperative PET plus 18-fluorodeoxyglucose (18F-FDG) among 202 patients (mean age, 64.7 years; 58% men; 92.6% white) with borderline resectable/locally advanced pancreatic cancer who received first-line neoadjuvant therapy with either modified FOLFIRINOX (leucovorin, 5-FU, irinotecan and oxaliplatin) or gemcitabine and nab-paclitaxel (Abraxane, Bristol Myers Squibb).
Researchers compared metabolic and biochemical responses after neoadjuvant therapy as preoperative predictors of pathologic responses, recurrence-free survival and OS.
Findings
Most patients (58%) had optimal CA 19-9 levels after neoadjuvant therapy. Moreover, 51% had a major metabolic response and 38% had a major pathologic response. Researchers reported median recurrence-free survival of 21 months and median OS of 48.7 months.
Metabolic response appeared superior to biochemical response in predicting pathologic response (area under the curve, 0.86 vs. 0.75; P < .001), highly correlated with pathologic response regardless of biochemical response (P = .001) and was the only univariate preoperative predictor of OS (OR = 0.25; 95% CI, 0.13-0.4).
Metabolic response remained the largest independent preoperative predictor (P < .001) for pathologic response (OR = 43.2; 95% CI, 16.9-153.2), recurrence-free survival (HR = 0.37; 95% CI, 0.2-0.6) and OS (HR = 0.21; 95% CI, 0.1-0.4) in a multivariate adjustment.
Implications
“Previously, we needed to wait until after complex surgery to tell how the pancreatic cancer responded to the neoadjuvant therapy,” Abdelrahman said in a press release. “With FDG-PET we can tell patients how the cancer responded to neoadjuvant therapy before going through major surgical resection. Going forward, we encourage providers to combine all available response measures to make suitable decisions about neoadjuvant therapy alterations and final decisions for surgery or no surgery on a case-by-case basis.”
An R01-funded clinical trial is underway at Mayo Clinic to further study use of PET for assessing treatment response in pancreatic ductal adenocarcinoma, according to Abdelrahman and colleagues.
“Although prospective studies are warranted, the results of FDG-PET for [this patient population] in this study may be sufficient to recommend FDG-PET as an approved adjunct modality in assessing neoadjuvant therapy efficacy in addition to the currently approved but poorly predictive metrics,” the researchers wrote. “We recommend that providers combine all available response measures (ie, clinical, radiologic, biochemical and metabolic) to make suitable decisions regarding neoadjuvant therapy alterations and final decisions for surgery or no surgery on a case-by-case basis.”
References :
- Abdelrahman AM, et al. J Natl Compr Canc Netw. 2022;doi:10.6004/jnccn.2022.7041.
- New study in JNCCN suggests way to predict outcomes with high accuracy prior to surgery for pancreatic cancer patients (press release). Published Sept. 8, 2022. Accessed Sept. 8, 2022.
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