Poor performance in incremental shuttle walk and cardiopulmonary exercise testing predicts poor overall survival for patients undergoing esophago-gastric resection

Abstract

Introduction

Esophageal and gastric cancer have a poor prognosis and surgical intervention is associated with considerable morbidity, highlighting the need for careful preoperative assessment. The Incremental Shuttle Walk Test (ISWT) and Cardiopulmonary exercise testing (CPET) can assess preoperative fitness. This study aims to investigate their correlation with both postoperative respiratory complications and overall survival.

Patients and methods

Patients were identified who underwent esophageal or gastric resections for cancer between 2010 and 2014 and had ISWT and/or CPET assessments. Tumor differentiation, stage, postoperative respiratory complications, and outcome were documented and then correlated with the results of the preoperative fitness assessments.

Results

Neither the ISWT result, anaerobic threshold (AT) nor VO2 Max correlated well with perioperative complications. However, ISWT (p < 0.001), AT (p < 0.001) and VO2 Max (p < 0.001) all correlated strongly with overall survival. No patient with a score of less than 350 m on ISWT survived beyond 3 years. In a subset of patients with ISWT results both pre and post chemotherapy (n = 49), those that had an improvement in result had a 19% incidence of post-operative respiratory complications compared to 45% where the result did not change or declined, though due to small numbers this only approached significance (p = 0.08).

Conclusion

ISWT and CPET can be useful preoperative tools to predict overall survival for patients undergoing esophago-gastric resection. Furthermore, patients that improve their functional status during chemotherapy seem to do better than those where it remains static or declines.

Introduction

The incidence of adenocarcinoma of the gastro-esophageal junction is rising faster than any other solid tumor in the western world [1], [2] but unfortunately the 5 year survival of patients diagnosed with the disease remains less than 20% and only rises to 40% when patients are considered operable and treated with the most recent combinations of chemo radiotherapy and surgery [3], [4]. Furthermore there are data to suggest that patients who survive less than two years never regain their preoperative quality of life after undergoing surgical resection and even those who do take up to one year to recover [5]. We are increasingly considering major surgery for patients who are older with significant co-morbidities. This is particularly relevant to the esophago-gastric cancer population as 58.5% of patients undergoing surgery are over the age of 70 [6], thus emphasizing the importance of careful multidisciplinary preoperative assessment [7].

The assessment of cardiopulmonary fitness before major surgery is required to identify patients who may be at increased operative risk [8] and to highlight comorbidity that can be optimized prior to surgery. Cardiopulmonary fitness assessment can also assist planning the perioperative support that patients may need following their operation as poor exercise tolerance has been correlated with increased risk of post-operative complications [9]. Neoadjuvant chemotherapy is now the standard of care for most patients undergoing treatment for esophago-gastric cancer but a significant proportion of patients will deteriorate in general fitness during their treatment, and this can be difficult to quantify.

There are a number of ways to assess cardiopulmonary fitness. Cardiopulmonary exercise testing (CPET) assesses functional capacity and is a reliable, noninvasive, and objective assessment to evaluate the response of the cardiovascular and respiratory systems to an increase in oxygen demand by measuring the anaerobic threshold (AT) and VO2 max [10], [11]. An AT of greater than or less than 11 [10], [12] and a VO2 Max of greater than or less than 14 [13] are associated with significant differences in operative mortality. However, it requires specialist equipment and trained operators to conduct and interpret the findings.

An alternative method is the incremental shuttle walk test (ISWT) [14] which is a simple and inexpensive method of assessing functional capacity. ISWT involves a shuttle walk exercise between two cones placed 10 m apart, which is externally paced by audio cues. The participant is required to increase their walking speed to keep up with the pre-determined pace. The result is the distance walked which equates to the number of 10 m shuttles completed. The ISWT provokes a graded cardiovascular response due to being progressive and incremental [15]. Those achieving an ISWT result of greater or less than 350 m have a lower or higher operative risk respectively [8]. Studies have suggested that ISWT and CPET tests correlate well with each other [16], [17].

As part of a perioperative enhanced recovery program an assessment of patient fitness was undertaken at initial presentation with OG cancer. The intention was to provide a baseline level of physical function with a subsequent reassessment after neoadjuvant treatment in order to determine the need for optimization and any deconditioning effect of the preoperative regimen. If a patient requires optimization, they are referred to physiotherapy to complete 4–6 weeks of exercise intervention, in the form of supervised cardiovascular and strengthening exercises which are specific and tailored to the patient's needs. In addition to the physiotherapy assessments, all patients undergoing major surgical resections will have an anesthetic pre-operative assessment. This will often include a CPET but this usually occurs after the completion of neo-adjuvant treatment.

The aim of the study was to evaluate preoperative assessments in predicting postoperative respiratory complications and longer term outcome and to determine whether ISWT could quantify the effects of de-conditioning from neo-adjuvant chemotherapy.