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Journal of Clinical Oncology, Vol 25, No 10 (April 1), 2007: pp. 1301-1302 © 2007 American Society of Clinical Oncology. DOI: 10.1200/JCO.2007.10.6682
Effectiveness After 1 Year of a Short-Term Physical Activity Intervention on Cardiorespiratory Fitness in Cancer PatientsThe Cancer Clinic, Rikshospitalet-Radiumhospitalet Medical Center, University of Oslo, Norway
School of Pharmacy, University of Oslo, Norway
The Cancer Center, Ullevaal University Hospital, Norway
The Cancer Clinic, Rikshospitalet-Radiumhospitalet Medical Center, University of Oslo, Norway To the Editor: In 2005 we published a randomized study in Journal of Clinical Oncology,1 evaluating the effectiveness of a 3-month home-based training program on cardiorespiratory fitness (CRF) and quality of life parameters in cancer patients shortly after curative chemotherapy. This low-cost training program had beneficial effect on maximum oxygen uptake (VO2max [mL/kg-1/min-1]), representing the CRF. In this communication we will briefly report on the results from the 6- and 12-month follow-up evaluations, by answering the following question: does the beneficial 3-month effect on VO2max persist until the 6- and 12-month follow-ups? Recent published reviews conclude that physical exercise has promising effects on a broad range of quality of life parameters in cancer patients. However, the majority of the studies performed are with relatively short intervention periods and without follow-up evaluations.2-4 Optimally such exercise interventions should lead to long-standing lifestyle changes and thereby continually beneficial effects in these patients. Two studies5,6 have reported 1-year effects of short-lasting training programs in cancer patients, observing that improvements in fatigue, physical training, physical strength, and fighting spirit were maintained over the entire year of follow-up. As far as we know, no studies have reported the long-term effects of short-lasting training programs on CRF in cancer patients. Our previous article contained detailed information about the study.1 Among 220 patients invited, 139 consented to participate and were randomly assigned to an intervention (n = 69) or a control group (n = 70) at baseline. At the 3-month evaluation 59 patients remained in the intervention group and 52 patients in the control group. Between the 3- and 6-month evaluations, nine patients dropped out of each group and from the 6- to the 12-month follow-ups an additional nine patients left the intervention group and seven patients left the control group. At the 6- and 12-month follow-ups, no intergroup differences in types of performed activities or the numbers of activities per patients were observed. Repeated analysis of variance was used to analyze the effect on CRF of the intervention over time. Scores at 3-, 6-, and 12 month follow-ups were included as dependent variables and groups (intervention or control) and baseline score served as explanatory variables. Furthermore, activity before diagnosis, age, sex, diagnosis, and stage of the disease were each included as additional covariates in the models. The analyses were based on those patients who provided data for all points of assessment. In order to assess robustness of estimates, we also performed intention-to-treat analyses with last observation carried forward for all patients who had a baseline measurement registered. Table 1 displays the crude VO2max values over time in each group. The CRF developed differently in the two groups. In the intervention group VO2max decreased over time, whereas it increased in the control group. There was a significant group by time interaction (P = .028). Adjusted for baseline values, the effect of the intervention on VO2max persisted until the 6-month follow-up, but not to the 12-months follow-up. The mean VO2max difference between the groups at 3, 6, and 12 months were 3.61, 2.74, and 0.18, respectively. The estimated difference in VO2max between the groups over the whole period of time was 2.12 mL (95% CI, –0.70 to 4.95; P = .139). The corresponding estimate in the intention-to-treat population (n = 139) was 1.92 (95% CI, 0.19 to 3.81; P = .048).
Our longer lasting and favorable effect on CRF in the intervention group at the 6-month follow-up could have been either due to the previous temporary short-lasting exercise program or to continued exercise during follow-up. We found that contrary to the 3-month observation, the 6- and 12-month observations show no intergroup differences in mean number of activities performed weekly or in number of patients performing different activities at the 6-month and 12-month follow-ups. This finding indicates that the beneficial effect on CRF at the 6-month follow-up were not due to the subjects' ongoing exercise, but to the previous intervention program. We conclude that in order to change a cancer patient's lifestyle more permanently and thereby gain beneficial effects over time, a longer intervention or booster sessions are probably necessary. AUTHORS' DISCLOSURES OF POTENTIAL CONFLICTS OF INTEREST The authors indicated no potential conflicts of interest.
ACKNOWLEDGMENTS This project has been supported by the Norwegian Foundation for Health and Rehabilitation and The Norwegian Cancer Society. We thank Inger Sandvik and Randi Bergersen for helpful assistance with performing physical tests, and the Sports Aerobic Training Center for giving patients free entrance to perform strength training and aerobic exercise. REFERENCES
1. Thorsen L, Skovlund E, Stromme SB, et al: Effectiveness of physical activity on cardiorespiratory fitness and health-related quality of life in young and middle-aged cancer patients shortly after chemotherapy. J Clin Oncol 23:2378-2388, 2005 2. Jones LW, Demark-Wahnefried W: Diet, exercise, and complementary therapies after primary treatment for cancer. Lancet Oncol 7:1017-1026, 2006[CrossRef][Medline] 3. McNeely ML, Campbell KL, Rowe BH, et al: Effects of exercise on breast cancer patients and survivors: A systematic review and meta-analysis. CMAJ 175:34-41, 2006 4. Conn VS, Hafdahl AR, Porock DC, et al: A meta-analysis of exercise interventions among people treated for cancer. Support Care Cancer 14:699-712, 2006[CrossRef][Medline] 5. Carlson LE, Smith D, Russel J, et al: Individualized exercise program for the treatment of severe fatigue in patients after allogeneic hematopoietic stem-cell transplant: A pilot study. Bone Marrow Transplant 37:945-954, 2006[CrossRef][Medline] 6. Berglund G, Bolund C, Gustafsson UL, et al: One-year follow-up of the ‘Starting Again’ group rehabilitation programme for cancer patients. Eur J Cancer 30:1744-1751, 1994[CrossRef]
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Copyright © 2007 by the American Society of Clinical Oncology, Online ISSN: 1527-7755. Print ISSN: 0732-183X
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