GIST Survival Statistics

/GIST Survival Statistics
GIST Survival Statistics 2018-07-11T12:15:52+00:00

One of the first questions that comes to mind for newly diagnosed cancer patients is, “Am I going to die from this, and if so, when?” Factors affecting survival for GIST include: how early GIST was found, a person’s general health status, type of GIST (mutation type, etc.), age, and even gender. It’s very natural to look up statistics on survival and then immediately apply whatever number you find to your situation. The truth is that survival statistics are numbers that apply to large groups of people. Thus, one cannot use survival statistics to predict what will happen to a specific individual. In 2012, the LRG published a paper on survival of its members in BMC Cancer, Survival of gastrointestinal stromal tumor patients in the Imatinib era: life raft group observational registrywhich details the research we had collected on patient survival to date.

Median? Median means in the middle. So a median survival of 10 years would mean that half survived less than 10 years and half survived more than 10 years.

Risk of recurrence is important in understanding survival statistics

Risk of recurrence calculates the likelihood that a GIST will return after surgery.  Keep in mind that this is an estimated probability that the disease will return based on a factor that the patient DOES NOT take any medication prescribed for treating GIST. Thus, estimating risk of recurrence for someone who has already taken drug therapy will be different, in many cases lowered as the drug has affected the natural trajectory of the disease. Other cases, such as GIST with tumor mutations (PDGFRA Exon 18 in the D842V, wildtype) may have a different disease course to which risk estimation may not be applicable.

So, what are the survival statistics for GIST?

  1. Patients who have a low risk of recurrence usually have a better prognosis and therefore a normal life expectancy after surgery. In a study of patients diagnosed with GIST followed up over time in Sweden, no instances of recurrence were observed for the very low risk and only 2.4% was observed in the low risk group (5). The population based Icelandic GIST Study also observed no instances of recurrence in the very low risk and low risk patients (6). However, while metastases may not be as common in very low risk patients, they can occur. In a 2016 population based US study that looked specifically at GIST tumors < 2cm in size, which would be classified as very low risk per the modified NIH method, the researchers noted that recurrence did in fact occur. Of the sample of 378 patients, 79.4% presented with localized disease, while 11.4 % had regional or distant metastatic disease and remaining 9.2 % of patients had missing or unknown stage data (7).
  2. Other GIST patients will have a higher risk of recurrence and tend to have a lower overall survival time than those with low-risk GIST. Research has shown that those with high-risk GIST who take three years of imatinib post-surgery have significantly improved survival rates compared to those who only took one year of imatinib  post-surgery (4). This study led to the FDA’s approval of the three-year prescription of adjuvant (post-surgery) imatinib.  This in turn raises the question of whether or not three years is sufficient or whether even longer adjuvant medication periods are needed for GIST patients with a high-risk of recurrence after surgery. Currently, there is a randomized phase III clinical trial that is studying three versus five years of adjuvant imatinib therapy for patients with a high risk for recurrence and the results are forthcoming. The clinicaltrials.gov page for that trial can be accessed at https://www.clinicaltrials.gov/ct2/show/NCT02413736. As a group, patients with metastatic GIST appear to have a lower overall survival than those without metastatic disease. However, a significant number of metastatic patients have achieved durable effects on overall survival with imatinib treatment for over 10 years (8).
  3. Mutation is believed to play a significant role in prognostication for progression free survival and overall survival as it correlates to clinical response to imatinib. Rates were significantly higher for patients with Kit exon 11-mutant GIST when compared with patients with Kit exon 9 mutant or wild type GIST (9). There have been a few clinical trials for patients with pediatric-type GIST with reports of very long survival for some patients with pediatric-type GIST and Carney’s Triad (a form of pediatric-type GIST). The LRG Registry study published in 2012 confirms these reports (3). Research published by Rutkowski, et.al., in 2014, showed a somewhat different picture when overall survival of 279 advanced GIST patients with a variety of mutations (exon 11, exon 9, wild type, and D842Vs), treated with imatinib, were compared. Their conclusion was that the ratio of overall survival of patients with advanced GIST with a mutation other than exon 11 KIT mutation treated with imatinib (except D842Vs) is similar to the ratio of overall survival of patients with exon 11 KIT mutation (10). While this may mean that the effect of mutation on survival is still a topic to be studied in order to gain clearer insights, it also shows that mutations that are non-responsive to treatment should still be identified, and thus echoes the need to obtain mutational testing whenever possible.
  4. Younger patients tend to do better than older patients and females tend to do somewhat better than males as observed in a study conducted by the Life Raft Group (3).

Survival of metastatic GIST patients in clinical trials

The following survival data for metastatic GIST comes from a phase II trial and from two large phase III trials. Note that only about 15%-20% of GIST patients have metastatic GIST at diagnosis.

Overall Survival times for patients with Metastatic GIST treated in randomized clinical trials
Trial
Phase
Patients
Median Overall Survival
B2222 (first GIST trial)
2
147
57 months
US/Canada (S0033)
3
746
55/51 months
Europe/Australia (EORTC trial)
3
946
45 months
Note: These survival times only includes survival from the time the patient entered the trial; not from the time of diagnosis. These three trials started in 2000 and 2001. The approval of Sutent in 2006, Stivarga in 2013, and availability of off-label treatments may have improved and increased survival times compared to these early trial results.

Impact of adjuvant imatinib treatment in survival outcomes

Data for adjuvant treatment comes from a randomized phase III trial conducted in Europe comparing one year of preventative (adjuvant) Gleevec after surgery to 3 years of adjuvant Gleevec (4). It’s important to note that this trial was only for GIST patients with a high-risk of recurrence.

Preventative Treatment after Surgery for High Risk GISTs , 1 year imatinib vs 3 years imatinib
Trial
1 year imatinib
3 years imatinib
Five year overall survival rate
81.7%
93.9%
P=0.02
Five year recurrence-free rate
47.9%
65.6%
P=>0.001

Survival of GIST Patients in the imatinib-era as observed in the Life Raft Group GIST Patient Registry

The Life Raft Group maintains a GIST Patient Registry that currently has over 1700 patients. This registry includes all types of GIST patients- young, old, low-risk, high-risk, metastatic and those with no evidence of disease (NED). The survival time measured from date of GIST diagnosis varies immensely in this group, from less than 1 month to almost 40 years (the longest survivor was diagnosed almost 30 years prior to the Gleevec-era). Please note, because the LRG is driven by voluntary internet participation, our membership may not be indicative of all GIST patients. For example, younger patients may be more likely to use the internet than older patients and patients with low or very low-risk GISTs may be less likely to join the Life Raft Group. For example, about 80% of Patient Registry members for which we have risk data (and excluding those with metastatic disease at time of diagnosis) are in the high-risk category for risk of recurrence. This compares to just 23% in the general population. The LRG Patient Registry also has a higher percentage of patients that were metastatic at the time of diagnosis, in a population-based study. As a result, we can conclude that the Patient Registry may be biased towards higher risk patients. Therefore, it may underestimate actual survival of all GIST patients. While we have yet to analyze all of the different subgroups in the Patient Registry, we can share some general numbers that apply to the group as a whole and a few different subsets. As of the end of 2016, survival (from the time of diagnosis) for the entire Patient Registry, including pediatric-like GIST, adult GIST, and those in all stages (NED, metastatic, etc):

  • The median overall survival when all groups were combined was 12 years from the time of diagnosis.
  • The 5-year overall survival rate when all groups were combined was 79%.
  • Patients diagnosed prior to age 18 did better as a group than those diagnosed over age 35.
    • The median overall survival for those diagnosed under age 18 has not been reached
  • The median overall survival for those diagnosed between 18 and 35 was 15.6 years.
  • The median overall survival for those diagnosed over age 35 was 11.3 years with females doing slightly better than males.
  • Of those who know their risk, about 54% of patients in the Patient Registry had metastatic disease at diagnosis. The median overall survival for those diagnosed over the age of 18 with metastatic disease at the time of diagnosis was 6.4 years. A significant number of patients are still responding to Gleevec taken to treat metastatic disease for over 10 years .

In summary, although it’s natural to want to know “How long do I have?”, remember that everyone is different and the “median” is just the number in the middle; half of all patients exceed this number and some of them far exceed it.

References

  1. Gastrointestinal Stromal Tumor Meta-Analysis Group (MetaGIST). Comparison of Two Doses of Imatinib for the Treatment of Unresectable or Metastatic Gastrointestinal Stromal Tumors: A Meta-Analysis of 1,640 Patients. J Clin Oncol 2010, 28:1247–1253.
  1. Blanke,C.D, Rankin,C., Demetri, G.D., Ryan, C.W., Von Mehren, M., Benjamin, R.S.,…Borden, E.C. Phase III Randomized, Intergroup Trial Assessing Imatinib Mesylate At Two Dose Levels in Patients With Unresectable or Metastatic Gastrointestinal Stromal Tumors Expressing the Kit Receptor Tyrosine Kinase: S0033. DOI: 10.1200/JCO.2007.13.4452 Journal of Clinical Oncology 26, no. 4 (February 2008) 626-632.
  1. Call, J., Walentas, C.D., Eickhoff, J.C. and Scherzer, N. Survival of gastrointestinal stromal tumor patients in the imatinib era: life raft group observational registry. BMC Cancer 2012, 12:90.
  1. Joensuu H, Eriksson M, Sundby Hall K, Hartmann JT, Pink D, Schütte J, Ramadori G, Hohenberger P, Duyster J, Al-Batran S-E, Schlemmer M, Bauer S, Wardelmann E, Sarlomo-Rikala M, Nilsson B, Sihto H, Monge OR, Bono P, Kallio R, Vehtari A, Leinonen M, Alvegård T and Reichardt P. One vs Three Years of Adjuvant Imatinib for Operable Gastrointestinal Stromal Tumor. JAMA. 2012;307(12):1265-1272. doi:10.1001/jama.2012.347
  1. Nilsson, B., Bümming, P., Meis-Kindblom, J. M., Odén, A., Dortok, A., Gustavsson, B., Sablinska, K. and Kindblom, L.-G. (2005), Gastrointestinal stromal tumors: The incidence, prevalence, clinical course, and prognostication in the preimatinib mesylate era. Cancer, 103: 821–829. doi:10.1002/cncr.20862
  1. Tryggvason, G., Gíslason, H. G., Magnússon, M. K. and Jónasson, J. G. (2005), Gastrointestinal stromal tumors in Iceland, 1990–2003: The Icelandic GIST study, a population-based incidence and pathologic risk stratification study. Int. J. Cancer, 117: 289–293. doi:10.1002/ijc.21167
  1. Coe, T. M., Fero, K. E., Fanta, P. T., Mallory, R. J., Tang, C.-M., Murphy, J. D., & Sicklick, J. K. (2016). Population-Based Epidemiology and Mortality of Small Malignant Gastrointestinal Stromal Tumors in the USA. Journal of Gastrointestinal Surgery : Official Journal of the Society for Surgery of the Alimentary Tract, 20(6), 1132–1140.
  1. Demetri, G.D., Rankin, C.J., Benjamin, R.S, Borden, E.C., Ryan, C.W., Priebat, D.A,…Blanke, C.D. (2014). Long-term disease control of advanced gastrointestinal stromal tumors (GIST) with imatinib (IM): 10-year outcomes from SWOG phase III intergroup trial S0033. J Clin Oncol 32:5s, 2014 (suppl; abstr 10508)
  1. Debiec-Rychter, M., Sciot,R., Le Cesne, A., Schlemmer,M., Hohenberger, P.,  Van Oosterom, A.t.,…Judson,I.KITmutations and dose selection for imatinib in patients with advanced gastrointestinal stromal tumours. European Journal of Cancer, Volume 42, Issue 8, 1093 – 1103
  1. Osuch, C., Rutkowski, P., Brzuszkiewicz, K., et al. (2014). The Outcome of Targeted Therapy in Advanced Gastrointestinal Stromal Tumors (Gist) with Non-Exon 11 Kit Mutations.Polish Journal of Surgery 86(7), pp. 325-332. Retrieved 24 Mar. 2017, from doi:10.2478/pjs-2014-0057, https://www.degruyter.com/view/j/pjs.2014.86.issue-7/pjs-2014-0057/pjs-2014-0057.xml

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