In the United States in 2015 it was estimated that there were 221,220 new lung cancer diagnosis and 158,040 lives lost, with a 5-year relative survival rate reported to be as low as 18.0% (Siegel et al., 2015). Stereotactic Ablative Radiotherapy (SABR) is increasingly being used as a primary treatment for early stage lung carcinoma as well as in the treatment of oligometatstic lesions in selected patients. SABR involves the delivery of a small number of large, highly focused doses of radiation over few fractions using multiple small fields or arcs. A major proposed advantage of SABR over conventional external beam radiotherapy is reduced radiation toxicity as a result of a sharp dose gradient fall off beyond the tumour, and it has recently been reported to be as effective as surgery for early lung cancer with regard to treatment tolerance and survival outcomes (Chang et al., 2015; Videtic et al., 2013; Zimmermann et al., 2005).
A growing body of research has demonstrated numerous health benefits from exercise participation during and after cancer treatment (Fuller et al., 2018; Speck et al., 2010). In 2010, the American College of Sports Medicine (ACSM) released a roundtable consensus on exercise guidelines for cancer survivors that included evidence for the introduction or maintenance of exercise during treatment (Schmitz et al., 2010). These guidelines suggest that, unless specifically contraindicated, the goal for cancer patients and survivors should be the same as for age-matched healthy adults. Exercise can improve outcomes for cancer survivors by preserving muscle mass (Winters-Stone et al., 2011; Galvao et al., 2009) and cardiovascular health (Courneya et al., 2007; Courneya et al., 2003), attenuating fatigue (Fuller et al., 2018) and enhancing quality of life (Schneider et al., 2007; Courneya et al., 2003). However, while the ACSM guidelines recommend that cancer survivors aim to complete at least 150 minutes per week of moderate-intensity exercise or 75 minutes of vigorous-intensity exercise (Speck et al., 2010), they also point out that given the diversity of cancers and treatment regimens, some of which may impact on the capacity to engage in exercise, a "one size fits all" approach to exercise prescription is not appropriate. As SABR is a newer treatment approach there are no published data indicating whether exercise can be maintained whilst undergoing treatment, the major side effect of which is fatigue (Lagerwaard et al., 2012; Haasbeek et al., 2011). The aim of this case study was to determine whether the ACSM exercise guidelines could be adhered to during SABR to the lung, and secondly to report on any changes in physiological or psychological function or wellbeing.
A 57-year-old male (height: 1.87m; mass: 93kg) presented for an opinion regarding treatment for a metastatic renal cell carcinoma situated in the superior lobe of the left lung. The metastasis was detected on routine follow-up Computed Tomography imaging. It developed at the site of previous metastectomy for pathologically proven renal cell carcinoma. Aside from the renal metastasis, the patient presented in good health, had professional qualifications in exercise science and was completing 435 minutes of gym-based moderate-intensity exercise per week, which is above the minimum threshold of the ACSM guidelines for healthy populations and cancer survivors. Weekly exercise included 5 x 60 minutes of cycling on a stationary bike at a moderate intensity (rating of perceived exertion [RPE] = 13) and 3 x 45 minutes of resistance exercise.
The patient's previous oncology history included a parotidectomy to remove pleomorphic adenomas (January 2010), a thyroidectomy via full neck dissection for papillary thyroid cancer (October 2010), a simple left nephrectomy to treat stage 1 renal cell carcinoma (November 2010), radioactive iodine treatment to treat papillary thyroid cancer (December 2010), external beam radiotherapy (30 fractions over 6 weeks) to treat thyroid cancer N1b-spread to lymph nodes at other cervical levels on the sides of the neck (February 2011), a robotic-assisted laparoscopic radical prostatectomy for stage 1 prostate cancer (June 2013), and a metastectomy for pathologically proven renal cell carcinoma to the superior lobe of the left lung (December 2013). The stage 2 renal carcinoma reoccurred in the superior lobe of the left lung at the time of this case study (June 2015).
The renal cell metastasis in the left lung was treated with a course of SABR that consisted of 48 Gy in four fractions on alternate days (i.e. over an 8-day period) dosed to the 74% isodose line using a 3D conformal SABR technique. Outcome measures were assessed prior to SABR treatment and then fortnightly for 12 weeks. All measurements were recorded at least 4 hours fasted and 24 hours after any exercise. The patient's treating medical team were made aware of all symptoms throughout the study. The patient provided written informed consent prior to participation. The University of South Australia Human Research Ethics Committee indicated that ethical approval was not required for this study because the patient is an author of the case study and consents to its publication. All procedures conformed to the Declaration of Helsinki.
The exercise program was advised and monitored by an Accredited Exercise Physiologist (AEP; Exercise and Sport Science Australia, QLD, Australia). The patient maintained his pre-diagnosis exercise regime throughout the observation period. Aerobic exercise was performed on a stationary bicycle at 60-70% maximum heart rate (HR max), which was equivalent to the patient's pre-treatment aerobic exercise intensity of RPE 13. HR based intensity was used instead of RPE because the patient's high fatigue made it difficult for him to perform any exercise at all without exceeding RPE 13.
Resistance training involved 6 exercises (chest press, upright seated row, triceps extension, biceps curl, chest fly, shoulder extension) performed using 3 sets of 8-10 repetitions for each exercise. Progression of resistance training focused on increasing resistance and then repetitions whereby once three sets of ten repetitions could be accomplished weight was increased to the next increment. Exercise progression took into consideration degenerative changes in the shoulder of the patient. Progression was delayed if increasing the exercise resistance caused large increases in shoulder pain.
Primary outcome measure
The primary outcome of interest was continued adherence to the patient's pre-treatment exercise program. Adherence was defined as a composite measure comprising scores of exercise session attendance, exercise intensity compliance and exercise contamination. Attendance referred to the number of minutes of exercise achieved per week as a percentage of the number of minutes prescribed. The patient recorded physical activity using the Godin leisure time index (Godin and Shephard, 1997). Contamination referred to any change in physical activity modes from baseline participation (i.e. commencing a new type of exercise program). Compliance referred to meeting the prescribed intensity of exercise and was reported as a percentage. Aerobic exercise compliance was based on the patient's ability to meet the prescribed intensity of 60-70% HR max. Mean aerobic exercise compliance was calculated across exercise sessions. Resistance exercise was prescribed in sets and repetitions and the percentage of the total prescribed load was used to measure compliance. For example, if 3 x 8 repetitions of a 20 kg biceps curl were prescribed the total prescribed load was 480 kg, and if 3 x 6 20 kg repetitions were completed, compliance was 360/480 = 75%. This process was repeated for each resistance exercise and session to determine the mean resistance exercise compliance. Overall compliance was defined as the mean of aerobic and resistance exercise compliance. Overall adherence was calculated as the mean of overall compliance and attendance plus or minus any contamination. Exercise test protocols performed for the purpose of this case study were not considered as contamination.
Secondary outcome measures
Maximal oxygen uptake (V[O.sub.2Max]) was measured using an indirect calorimeter (ParvoMedics TrueOne 2400, Parvo Medics, USA) during an incremental exercise test to exhaustion on an electronically braked cycle ergometer (Ergoselect 200, Ergoline, Germany). HR was recorded throughout using a personal HR monitor (RS800CX, Polar Electro OY, Finland) to facilitate prescription of relative aerobic exercise intensity. A ramp protocol was used where power output commenced at 80 watts and increased by 15 watts per minute until exhaustion. The criteria for a valid V[O.sub.2Max] test was identified as a plateau in VO2 with increasing exercise intensity and an RER >1.1 based on the most commonly used criteria in previous studies (Midgley et al., 2007). An additional sub-maximal perceptually regulated exercise test (PRET) to predict V[O.sub.2Max] was performed on alternate weeks to the actual V[O.sub.2Max] testing and comprised 4 stages of 3-minute duration at RPE 9, 11, 13, and 15 based on the Borg 6-20 scale (Borg, 1998). This was conducted in accordance with the validated methodology published previously (Eston et al., 2008). The participant adjusted the power output of the bike to achieve the necessary RPE during the first 30 seconds of each 3-minute exercise stage. Power output, HR and V[O.sub.2] were recorded during each 3-minute exercise stage to assess effects of SABR on the relationship of RPE with power output, HR and V[O.sub.2]. A difference of 7.5% was considered the minimal detectable change in V[O.sub.2Max] based on previous test-retest data collected in older adults (Kohrt et al., 1991).
The patient's 8-repetition maximum (8RM) for the seated row and biceps curl was used...