A total of 168 patients were enrolled in the present study. A total of 53 patients (31.5%, 36 men, 17 women) were diagnosed with depression. CRC patients showed markedly lower serum concentrations of 25-hydroxyvitamin D (25(OH)D) as compared to normal controls (45.12 ± 15.45 vs. 63.14 ± 16.46 nmol/L, p < 0.001). No correlation was found between 25(OH)D and age and gender in patients with CRC. Patients with depression had poorer financial situation, less social support and more pain. Significant differences were found between patients with depression and those without depression in 25(OH)D concentration quartiles of CRC patients (p < 0.001). The proportion of patients in the lowest quartile (≤ 30.0 nmol/L) was significantly higher in the depression group (p < 0.001), while the proportion of patients in higher quartiles (43.1–55.0 and ≥ 55.1 nmol/L) was markedly lower in the depression group (p < 0.001 and p = 0.011, respectively) (Table 1).
Table 1
Demographic and clinical characteristics of the samples under study
Variables | Depressed (n = 53) | Not depressed (n = 115) | P value |
Sex | | | 0.088 |
Male | 36(67.9) | 92(80.0) |
Female | 17(32.1) | 23(20.0) |
Age | | | 0.398 |
≤ 50 year | 18(43.0) | 37(32.2) |
50–60 years | 24(45.3) | 43(37.4) 35(30.4) |
≥ 60 years | 11(20.8) |
Education | | | 0.443 |
≤ 6 years > 6 years | 35(66.0) | 73(63.5) |
18(34.0) | 42(36.5) |
Financial situation Poor | | | 0.013 |
34(62.4) | 50(43.5) 65(56.5) |
Satisfactory | 19(35.8) |
Marital status | | | 0.743 |
Married | 49(92.5) | 108(93.9) |
Not married | 4(7.5) | 7(6.1) |
Number of children | | | 0.993 |
0 | 8(15.1) | 15(13.0) |
1 | 14(26.4) | 32(27.8) |
> 1 | 31(58.5) | 68(59.1) |
Living situation | | | 0.342 |
With spouse and children Other living situation | 41(77.4) | 96(83.5) |
12(22.6) | 19(16.5) |
Social support < 4 4–6 | | | < 0.001 |
30(56.6) | 24(20.9) | < 0.001 < 0.001 |
13(24.5) | 70(60.9) |
> 6 | 10(18.9) | 21(18.3) | 0.925 |
Cancer stage | | | 0.332 |
Duke’s A or B Duke’s C or D | 25(46.3) | 44(38.3) |
29(53.7) | 71(61.7) |
Duration of CRC | | | 0.447 |
< 1 year | 20(37.7) | 35(30.4) 62(53.9) 18(15.7) |
1–2 years | 23(43.4) |
> 3 years | 10(18.9) |
Cancer treatments Surgery, yes |
50(94.3) | 104(91.7) | 0.552 |
Chemotherapy, yes | 44(83.0) | 91(79.1) | 0.556 |
Radiation, yes | 10(18.9) | 24(20.9) | 0.764 |
Other, yes | 2(3.8) | 3(2.6) | 0.651 |
Pain | | | < 0.001 |
No | 19(38.5) | 82(71.3) |
Yes | 34(64.2) | 33(28.7) |
25(OH)D | | | < 0.001 |
Quartile 1 | 26(49.1) | 13(11.3) | < 0.001 |
Quartile 2 | 19(35.8) | 28(24.3) | 0.123 < 0.001 |
Quartile 3 | 4(7.5) | 46(40.0) |
Quartile 4 | 4(7.5) | 28(26.1) | 0.011 |
Note: Values are shown as number (percentage); CRC, colorectal cancer; 25(OH)D, 25-hydroxyvitamin D. |
In logistic regression analysis, serum 25(OH)D concentrations (≤ 30.0 and ≥ 43.1 nmol/L) were independently associated with the presence of depression among CRC patients (OR, 8.840; 95% CI, 2.462–31.734, p = 0.001 and OR, 0.031; 95% CI, 0.008–0.124, p < 0.001, respectively). Additionally, less social support and pain were markedly associated with the presence of depression among CRC patients (OR, 4.351; 95% CI, 1.324–14.303, p = 0.015; OR, 6.358; 95% CI, 1.607–25.156, p = 0.008, respectively).
We excluded 38 patients for not meeting the predetermined supplementation criteria (n = 19) or because they declined our invitation (n = 19). Consequently, 130 (45 with and 85 without depression), began to take 2000 IU vitamin D3 per day for six months. Of these patients, the baseline characteristics were similar to those of the entire cohort. We observed reductions in HDRS-17 scores in depressed patients after 3 (9 vs.12, p < 0.001) and 6 months (8 vs. 12, p < 0.001). There was no change being observed in non-depressed patients (Fig. 1). The treatment response was consistent with the restoration of vitamin D concentrations, which increased to normal after 3 and 6 months in patients with (75.13 and 75.47 nmol/L, respectively) and without depression (76.71 and 77.07 nmol/L, respectively) (all p < 0.001). Specifically, we observed significant improvements (at least a 50% reduction from baseline in the total HDRS scores) in the majority of depressed patients after both 3 and 6 months.