Disease-free Interval Is Associated with Oncologic Outcomes in Patients with Recurrent Gastrointestinal Stromal Tumor

Adjuvant imatinib in high-risk resected gastrointestinal stromal tumors: Merely delaying the inevitable?

INTRODUCTION

Patients with high-risk resected gastrointestinal stromal tumors (GIST) receiving adjuvant imatinib have improved recurrence-free survival (RFS), however whether a complete cytocidal effect exists is unknown. We investigated this using a normalized recurrence timeline measured from end of oncologic treatment (EOOT), defined as the later of resection or end of adjuvant therapy.

METHODS

We reviewed patients with resected high-risk GIST at our cancer center from 2003 to 2018. RFS (measured from resection and EOOT), overall survival (OS), and time to imatinib resistance (TTIR) were analyzed using Kaplan-Meier analysis and multivariable Cox proportional hazards modeling. The performance of the Memorial Sloan Kettering (MSK) GIST nomogram was assessed.

RESULTS

We identified 86 patients with high-risk GIST with a median 106 months of postsurgical follow-up. One-third (n = 29; 34%) did not receive adjuvant imatinib, while 57 (66%) did for a median of 3 years. The MSK nomogram-predicted 5-year RFS for patients receiving adjuvant imatinib was similar to those who did not (29% vs. 31%, p = 0.64). When RFS was measured from EOOT, the MSK-predicted RFS was independently associated with EOOT RFS (hazard ratio 0.22, p = 0.02), while adjuvant imatinib receipt and duration were not. Neither receipt nor duration of adjuvant imatinib were associated with TTIR or OS (all p > 0.05).

CONCLUSIONS

Treatment with adjuvant imatinib delays, but does not clearly impact ultimate recurrence, TTIR, or OS, suggesting many patients with high-risk GIST may receive adjuvant imatinib unnecessarily. Additional studies are needed to establish the benefit of adjuvant therapy versus initiating therapy at first radiographic recurrence.

Ten-Year Survivorship in Patients with Metastatic Gastrointestinal Stromal Tumors

INTRODUCTION

Patients developing metastatic gastrointestinal stromal tumors (mGIST) have heterogenous disease biology and oncologic outcomes; prognostic factors are incompletely characterized. We sought to evaluate predictors of 10-year metastatic survivorship in the era of tyrosine kinase inhibitor (TKI) therapy.

METHODS

We reviewed patients with mGIST treated at our Comprehensive Cancer Center from 2003 to 2019, including only patients with either mortality or 10 years of follow-up. Ten-year survivorship was evaluated with logistic regression.

RESULTS

We identified 109 patients with a median age of 57 years at mGIST diagnosis. Synchronous disease was present in 57% (n = 62) of patients; liver (n = 48, 44%), peritoneum (n = 40, 37%), and liver + peritoneum (n = 18, 17%) were the most common sites. Forty-six (42%) patients were 10-year mGIST survivors. Following mGIST diagnosis, radiographic progression occurred within 2 years in 53% (n = 58) of patients, 2-5 years in 16% (n = 17), and 5-10 years in 16% (n = 17), with median survival of 32, 76, and 173 months, respectively. Seventeen (16%) patients had not progressed by 10 years. Fifty-two (47%) patients underwent metastasectomy, which was associated with improved progression-free survival (hazard ratio 0.63, p = 0.04). In patients experiencing progression, factors independently associated with 10-year survivorship were age (odds ratio [OR] 0.96, p = 0.03) and time to progression (OR 1.71/year, p < 0.001).

CONCLUSIONS

Ten-year survivorship is achievable in mGIST in the era of TKIs and is associated with younger age and longer time to first progression, while metastasectomy is associated with longer time to first progression. The role of metastasectomy in the management of patients with disease progression receiving TKI therapy merits further study.

Hepatic metastases in gastrointestinal stromal tumors: oncologic outcomes with curative-intent hepatectomy, resection of treatment-resistant disease, and tyrosine kinase inhibitor therapy alone

BACKGROUND

Hepatic resection for metastatic GIST (mGIST) is often performed with either curative-intent or for tyrosine kinase inhibitor (TKI)-resistant lesions. The efficacy of hepatectomy for treatment-resistant lesions (TRL) is uncertain.

METHODS

We reviewed patients with liver-mGIST treated from 2003 to 2018. Oncologic outcomes including overall (OS), post-operative progression-free survival (PFS), and post-progression OS were evaluated using Kaplan-Meier and Cox proportional hazards modeling.

RESULTS

We identified n = 91 patients; 31 (34%) underwent curative-intent hepatectomy, 60 (66%) were initially managed with TKI alone, and 17 (19%) had resection of a TRL. The median follow-up for resected patients was 102 months (range 5-209 months) with 23 (25%) managed with a major hepatectomy. Patients having curative-intent hepatectomy had 72% 10-year OS following diagnosis of liver-mGIST, compared with 58% (P = 0.50) for TRL resection and 41% (P = 0.01) for non-resected patients. Curative-intent hepatectomy (HR 0.39, P = 0.03) and age (HR 1.04, P = 0.004) were independently associated with 10-year OS, but not TRL resection. TRL resection was not associated with improved post-progression OS compared to second-line TKI therapy (HR 0.61, P = 0.21).

CONCLUSIONS

Curative-intent hepatectomy is associated with improved OS in liver-mGIST. The oncologic benefit of resecting treatment-resistant liver-mGIST compared to second-line TKI therapy alone remains unclear in the era of multi-line TKI therapy.

Early Versus Late Recurrence in Rectal Cancer: Does Timing Matter?

BACKGROUND

The definition of early recurrence (ER) in rectal cancer is unclear, and the association of ER with post-recurrence survival (PRS) is poorly described. We therefore sought to identify if time to recurrence (TTR) is associated with PRS.

METHODS

We reviewed all curative-intent resections of nonmetastatic rectal cancer from 2003 to 2018 in our institutional registry within an NCI-Designated Comprehensive Cancer Center. Clinicopathologic data at diagnosis and first recurrence were collected and analyzed. ER was pre-specified at < 24 months and late recurrence (LR) at ≥ 24 months. PRS was evaluated by the Kaplan-Meier method and Cox proportional hazards modeling.

RESULTS

At a median follow-up of 53 months, 61 out of 548 (11.1%) patients undergoing resection experienced recurrence. Median TTR was 14 months (IQR 10-18) with 45 of 61 patients (74%) classified as ER. There were no significant baseline differences between patients with ER and LR. Most recurrences were isolated to the liver (26%) or lung (31%), and 16% were locoregional. ER was not associated with worse PRS compared to LR (P > 0.99). On multivariable analysis, detection of recurrence via workup for symptoms, CEA > 10 ng/mL at recurrence, and site of recurrence were independently associated with PRS.

CONCLUSION

ER is not associated with PRS in patients with resected rectal cancer. Symptomatic recurrences and those accompanied by CEA elevations are associated with worse PRS, while metastatic disease confined to the liver or lung is associated with improved PRS. Attention should be directed away from TTR and instead toward determining therapy for patients with treatable oligometastatic disease.