Results of the search
The systematic searches yielded 10702 records, and 28 additional records were found by hand searching systematic reviews in this field. After removal of duplicates, we exported 6862 records to Rayyan for screening of title and abstract, after which we read 328 records as full-text manuscripts. One reviewer (JME) retrieved all full-text publications. We included 131 RCTs in our analysis.
Characteristics of the included studies
The 131 RCTs contributed information about 138 interventions to the analysis. The characteristics of the individual included studies/interventions such as country, year of publication, sample size, type of cancer reported, treatment stage, and other are presented in Additional file 3. Summary data are presented below.
Twenty-one trials (16%) provided study name or acronym, and forty-four (34%) reported their trial registry record/trial protocol. Hereafter we refer to interventions (rather than trials) as they represent our unit of analysis.
Overall, we report data from 38 countries. USA was the most common country across the analyzed interventions (38, 27%), followed by Australia (17, 12%), Canada (12, 9%), Germany (11, 8%), Korea (6, 4%), and Spain (5, 4%). Around half of the interventions were performed in groups of 10 to 50 participants (65, 47%), and one-third included 51 to 100 participants (47, 34%). Breast cancer was the most common type of cancer (69, 50%), followed by prostate cancer (20, 14%), mixed (more than one type) (14, 10%), and colorectal cancer (7, 5%). Most exercise interventions were administered to people receiving active cancer treatment (71, 51.4%), followed by post-treatment administration (62, 45%) and pre-operative administration (6, 4.3%).
Interventions: exercise modalities
Aerobic exercise was the most studied exercise modality (43, 30.5%) followed by combined aerobic/resistance training (40, 28.4%). Resistance training alone and yoga accounted for around 13% of the interventions each. Other modalities comprised Qigong, aquatic exercise, football, high-intensity training, and Tai-Chi. One-third of the exercise interventions were implemented in clinics or hospitals. On average, exercise interventions lasted 14.3 weeks (range 1 to 104 weeks), and involved 2.8 (range 1 to 14) sessions per week.
Completeness of reporting of the exercise training interventions
Total sample
Completeness of reporting ranged from 42% to 96% among the TIDieR items (see Figure 2). Intervention length was the most reported item across interventions (133, 96%), followed by study rationale (131, 95%), whereas provider (58, 42%) and how well (planned) item (63, 46%) were the two least reported items. Half of the TIDieR items were reported in 50% to 70% of the interventions, and only four items were reported in more than 80% of the interventions (items 2 and 8a-c). In addition, the seven items (3-9) deemed to be core for replication (25) exhibited a mean reporting of 71 %, ranging from 42% to 96%.
Subgroup analysis 1: breast cancer
Breast cancer exercise-training interventions counted for half of the total sample in this study. However, completeness of reporting among the interventions exhibited similar results to the total sample. The largest difference was a 17% less complete reporting of item 7 (where) than in the non-breast cancer subgroup. See Table 2.
Table 2. Completeness of reporting of the exercise interventions: total sample and type of cancer subgroups
TIDieR item
|
Total sample
n (%)
|
Breast cancer
n (%)
|
Non-breast cancer
n (%)
|
Item 1. Brief name
|
76 (55%)
|
36 (52%)
|
40 (58%)
|
Item 2. Why
|
131 (95%)
|
66 (96%)
|
65 (94%)
|
Item 3. What (Materials)
|
81 (59%)
|
40 (58%)
|
41 (59%)
|
Item 4. What (procedures)
|
108 (78%)
|
53 (77%)
|
55 (80%)
|
Item 5a. Who provided (disciplinary background)
|
93 (67%)
|
44 (64%)
|
49 (71%)
|
Item 5b. Who provided (expertise, experience, or specific training)
|
58 (42%)
|
30 (44%)
|
28 (41%)
|
Item 6. How
|
104 (75%)
|
54 (78%)
|
50 (72%)
|
Item 7. Where
|
92 (67%)
|
40 (58%)
|
52 (75%)
|
Item 8a. Frequency
|
123 (89%)
|
60 (87%)
|
63 (91%)
|
Item 8b. Length
|
133 (96%)
|
66 (96%)
|
67 (97%)
|
Item 8c. Duration
|
120 (87%)
|
63 (91%)
|
57 (83%)
|
Item 8d. Intensity
|
90 (65%)
|
39 (56%)
|
51 (74%)
|
Item 9. Tailoring
|
82 (59%)
|
37 (54%)
|
45 (65%)
|
Item 10. Modifications
|
70 (51%)
|
32 (46%)
|
38 (55%)
|
Item 11. How well (planned)
|
63 (46%)
|
30 (43%)
|
33 (48%)
|
Item 12. How well (actual)
|
70 (51%)
|
35 (51%)
|
35 (51%)
|
Subgroup analysis 2: non-breast cancer
The other half of the interventions, those that involved non-breast cancer patients, comprised predominantly prostate cancer (20, 29%), followed by mixed type and lung cancers (each 14, 20%), and colorectal cancer (7, 10%). In general, this subgroup was reported in a more complete manner than the breast cancer subgroup and the total sample. Only a few items showed lower scores of complete reporting relative to the other groups (Item 2, item 5b, item 6, and item 8c). See Table 2.
Subgroup analysis 3: exercise modality
Overall, aerobic exercise plus resistance training interventions had the lowest level of reporting relative to the other two subgroups (i.e., aerobic exercise and resistance training). Item 2 (why), item 8a (frequency), and item 8b (length) were completely reported in more than 90% of the interventions in all three subgroups. The last two items (items 8 a and b) reached 100% reporting in resistance training interventions. Item 5b (who provided, expertise) was the least reported item across the subgroups. See table 3.
Table 3. Completeness of reporting of by exercise modality: aerobic exercise; aerobic exercise plus resistance training; resistance training
TIDieR item
|
Aerobic exercise (n=43)
|
Aerobic exercise plus resistance training
(n=40)
|
Resistance training
(n=18)
|
|
n (%)
|
n (%)
|
n (%)
|
Item 1. Brief name
|
31 (72.1%)
|
18 (45%)
|
10 (55.6%)
|
Item 2. Why
|
40 (93%)
|
37 (92.5%)
|
18 (100%)
|
Item 3. What (Materials)
|
29 (67.4%)
|
17 (42.5%)
|
11 (61.1%)
|
Item 4. What (procedures)
|
34 (79.1%)
|
29 (72.5%)
|
16 (88.9%)
|
Item 5a. Who provided (disciplinary background)
|
32 (74.4%)
|
20 (50%)
|
10 (55.6%)
|
Item 5b. Who provided (expertise. experience. or specific training)
|
17 (39.5%)
|
12 (30%)
|
5 (27.8%)
|
Item 6. How
|
31 (72.1%)
|
26 (65%)
|
13 (72.2%)
|
Item 7. Where
|
35 (81.4%)
|
23 (57.5%)
|
10 (55.6%)
|
Item 8a. Frequency
|
40 (93%)
|
36 (90%)
|
18 (100%)
|
Item 8b. Length
|
40 (93%)
|
38 (95%)
|
18 (100%)
|
Item 8c. Duration
|
37 (86%)
|
32 (80%)
|
16 (88.9%)
|
Item 8d. Intensity
|
35 (81.4%)
|
34 (85%)
|
14 (77.8%)
|
Item 9. Tailoring
|
29 (67.4%)
|
23 (57.5%)
|
14 (77.8%)
|
Item 10. Modifications
|
15 (34.9%)
|
21 (53.8%)
|
15 (83.3%)
|
Item 11. How well (planned)
|
20 (46.5%)
|
18 (46.2%)
|
10 (55.6%)
|
Item 12. How well (actual)
|
24 (55.8%)
|
15 (39.5%)
|
12 (66.7%)
|