Table 1.
Characteristics of included studies
| Variables | Cancer studies* | Cancer surgical studies |
|---|---|---|
| No. of studies/total No. (%) | No. of studies/total No. (%) | |
| Cancer type | ||
| Gastrointestinal cancer | 7/33 (21.2) | 118/306 (38.6) |
| Lung cancer | 7/33 (21.2) | 89/306 (29.1) |
| Genitourinary cancer | 6/33 (18.2) | 67/306 (21.9) |
| Breast cancer | 5/33 (15.2) | 20/306 (6.5) |
| Thyroid cancer | 0 | 5/306 (1.6) |
| Head and neck cancers | 0 | 3/306 (1.0) |
| Hematopoietic and lymphoid cancers | 3/33 (9.1) | 0 |
| Skin cancer | 1/33 (3.0) | 0 |
| Nervous system cancer | 0 | 1/306 (0.3) |
| Advanced/metastatic cancer | 3/33 (9.1) | 0 |
| Others | 1/33 (3.0) | 3/306 (1.0) |
| No. of treatment groups | ||
| 2 | 32/33 (97.0) | 277/306 (90.5) |
| 3 | 1/33 (3.0) | 21/306 (6.9) |
| ≥4 | 0 | 8/306 (2.6) |
| No. of patients enrolled | ||
| Median | 4515 | 699 |
| Q1 to Q3 | 1392 to 20600 | 307 to 2783 |
| Not mentioned | 0 | 3/306 (1.0) |
| Propensity score methods type | ||
| Propensity score matching | 16/33 (48.5) | 207/306 (67.6) |
| Propensity score weighting | 9/33 (27.3) | 20/306 (6.5) |
| Propensity score stratification | 1/33 (3.0) | 27/306 (8.8) |
| Covariate adjustment using propensity score | 1/33 (3.0) | 31/306 (10.1) |
| More than one type | 6/33 (18.2) | 21/306 (6.9) |
| The proportion of matched sample size† | ||
| <25% | 2/21 (9.5) | 35/219 (16.0) |
| 25%–<50% | 6/21 (28.6) | 80/219 (36.5) |
| 50%–<75% | 3/21 (14.3) | 53/219 (24.2) |
| 75%–<100% | 6/21 (28.6) | 14/219 (6.4) |
| Not mentioned | 4/21 (19.0) | 12/219 (5.5) |
| Only reported the matched sample | 0 | 25/219 (11.4) |
*
Cancer studies in top medical and cancer journals in 2014 and 2015. Nine studies were included in both cancer studies and cancer surgical studies.
†
The reporting of the proportion of matched sample size was evaluated in studies utilizing matching.