Table 1 displays a comparative analysis of patients based on their body mass index (BMI) status. Among the 7134 breast cancer patients studied, 2026 (28.31%) had a BMI < 25 kg/m2, 3045 (42.6%) fell within the range of 25.0 ≤ BMI < 30.0 kg/m2, and 2063 (29.1%) had a BMI of 30 kg/m2 or higher. The mean age at diagnosis was similar across the three BMI groups, but there was a tendency for older patients to be more prevalent in the obese group (P > 0.05).
Premenopausal patients were more likely to have a lower BMI compared to postmenopausal patients, with almost half of the obese patients being in the postmenopausal period (58.9%). Menopausal status was significantly associated with BMI status (P < 0.001). The majority of patients were classified as grade 2 and stage 2 across the BMI categories (P = 0.12, P = 0.08, respectively).
The Luminal A molecular subtype was the most prevalent hormone receptor subtype across all BMI categories, while the Her2 molecular subtype positive was the least common hormone receptor subtype across all BMI categories (P = 0.14). The rate of patients undergoing axillary lymph node dissection (ALND) initially was higher compared to other Axillary Types across all BMI categories (P = 0.82). Hormone therapy was equally distributed among these three groups (P = 0.26). In all three groups, over 80% of patients did not receive preoperative chemotherapy (P = 0.02); however, postoperative chemotherapy was administered to over 80% of patients in all three groups (P = 0.14).
The highest proportion of patients undergoing axillary and chest radiotherapy had a BMI higher than 25 kg/m2, while this proportion was lower in patients with a BMI below 25 kg/m2 (P < 0.001).
Table 1
Comparative analysis of patient characteristics across body mass index (kg/m2) status of studied patients.
| BMI group | P-value |
BMI < 25 (n = 2026) | 25.0 ≤ BMI < 30.0 (n = 3045) | BMI ≥ 30 (n = 2063) |
Age at diagnosis,(Mean ± SD) (year) | 47.50 ± 12.17 | 48.64 ± 11.05 | 50.13 ± 10.33 | P > 0.05 |
Menopausal status Premenopausal | 1107 (54.6%) | 1510 (49.5%) | 846 (41.1%) | < 0.001 |
Postmenopausal | 919(55.4%) | 1550 (50.5%) | 1217 (58.9%) |
Pathology Tumor Grade | 1 | 363 (19.4%) | 498 (17.7%) | 336 (17.6%) | 0.12 |
2 | 1137 (60.8%) | 1739 (61.9%) | 1145 (59.9%) |
3 | 370 (19.8%) | 571 (20.3%) | 432 (22.6%) |
Axillary Type | ALND at first | 916 (45.2%) | 1357 (44.6%) | 924 (44.8%) | 0.82 |
SLNB only | 787 (38.8%) | 1230 (40.4%) | 823 (39.9%) |
SLNB then ALND | 323 (15.9%) | 458 (15.0%) | 316 (15.3%) |
Stage | 1 | 403 (32.5%) | 582 (29.9%) | 380 (28.2%) | 0.08 |
2 | 730 (58.9%) | 1172 (60.1%) | 820 (60.8%) |
3 | 107 (8.6%) | 195 (10.0%) | 149 (11.0%) |
Preoperative Chemotherapy | No | 1674 (81.1%) | 2574 (83.3%) | 1765 (84.0%) | 0.02 |
yes | 391 (18.9%) | 515 (16.7%) | 336 (16.0%) |
postoperative Chemotherapy | No | 309 (15.0%) | 416 (13.5%) | 272 (12.9%) | 0.14 |
yes | 1756 (85.0%) | 2673 (86.5%) | 1829 (87.1%) |
Axillary and Chest Radiotherapy | No | 541 (26.2%) | 700 (22.7%) | 442 (21.0%) | < 0.001 |
yes | 1524 (73.8%) | 2389 (77.3%) | 1659 (79.0%) |
Hormone therapy | No | 495 (24.0%) | 725 (23.5%) | 534 (25.4%) | 0.26 |
Yes | 1570 (76.0%) | 2364 (76.5%) | 1567 (74.6%) |
Hormone receptor | Luminal A | 1089(53.8%) | 1726 (56.7%) | 1223 (59.3%) | 0.14 |
Luminal B | 435 (21.5%) | 682 (22.4%) | 389 (18.9%) |
Her2 | 210 (10.4%) | 304 (10%) | 223(10.8%) |
Triple Negative | 292(14.6%) | 333 (10.9%) | 228(11%) |
Table 2 presents a comparative analysis of patient characteristics and menopausal status based on the BMI (kg/m2) status of the patients under study. Quadrantectomy (BCS) emerged as the most common type of surgery among both pre- and post-menopausal women in all three groups. Mastectomy was more prevalent among postmenopausal patients than premenopausal patients in all three groups (P < 0.001 for BMI < 25 and 25.0 ≤ BMI < 30.0 kg/m2, P = 0.6 for patients with BMI ≥ 30 kg/m2). Regardless of menopausal status, the majority of patients were classified as grade II based on BMI. Furthermore, stage 3 was more frequently observed in postmenopausal patients across all three groups (P = 0.16, P = 0.17, P = 0.51, respectively).
The incidence of multifocal breast tumors was higher in premenopausal patients compared to postmenopausal patients in all three BMI status groups. A statistically significant association was found between the presence of multifocal breast tumors and menopausal status across the three BMI status groups (P = 0.004, < 0.001, and 0.01, respectively).
A statistical examination of tumor grading across three defined categories indicated that the majority of premenopausal patients in all three groups were classified as grade II, regardless of BMI status. Conversely, postmenopausal in all three groups were predominantly classified as grade II. Notably, Grade III Permanent Pathology Tumors were more prevalent in premenopausal women compared to postmenopausal women in all three groups (P < 0.001, P = 0.01, and P = 0.01, respectively).
While the majority of patients did not exhibit tumor invasion across the three BMI categories, premenopausal patients displayed a higher prevalence of non-invasive tumors compared to postmenopausal patients. A statistically significant relationship was observed between the occurrence of various types of invasion and menopausal status in the studied population with a 25.0 ≤ BMI < 30.0 kg/m2 (P = 0.03). Vascular invasion was more frequently observed in postmenopausal patients across all three BMI categories. Both Vascular and Preneural invasion, as well as Lymphatic and Vascular invasion, displayed similar distributions based on menopausal status in all three BMI categories. Furthermore, a statistically significant correlation was noted between the occurrence of different invasion types and tumor subtypes (P < 0.001).
Axillary lymph node dissection (ALND) was the most common type of axillary surgery performed in postmenopausal patients within the BMI < 25 kg/m2 and 25.0 ≤ BMI < 30.0 kg/m2 groups. For postmenopausal patients with a BMI ≥ 30 kg/m2, ALND then SLNB were the predominant types of axillary surgeries performed (P = 0.56). Conversely, a higher proportion of patients in the premenopausal period underwent SLNB alone, regardless of BMI status. A statistically significant correlation was identified between the type of axillary surgery and menopausal status within the studied population with a BMI of 25.0 ≤ BMI < 30.0 kg/m2 (P = 0.002).
The Luminal A hormone receptor subtype was prevalent among all breast cancer patients, irrespective of menopausal or BMI status, while Luminal B was more commonly found in premenopausal patients compared to postmenopausal patients across all three BMI groups. A statistically significant variance was noted in the distribution of hormone receptor subtypes based on menopausal status within the three BMI groups (P < 0.001 for patients with BMI < 25 kg/m2 and BMI 25.0 ≤ BMI < 30.0 kg/m2, and P = 0.007 for patients with BMI ≥ 30 kg/m2, respectively).
Hormone therapy was provided to the majority of patients in all three groups regardless of menopausal status, with postmenopausal women receiving hormone therapy more frequently than premenopausal women across all BMI groups. A statistically significant relationship was found between hormone therapy and menopausal status in patients with a higher BMI of ≥ 30 kg/m2 (P = 0.006).
Radiotherapy was administered to a significant percentage of patients in all three BMI groups, with a higher prevalence among postmenopausal patients in all three groups (P < 0.001 in all groups). Postoperative chemotherapy was utilized in a considerable number of patients across all three groups, but it was more common among premenopausal patients in all three BMI groups (P = 0.01, P < 0.001, P = 0.01 in the three groups, respectively). Preoperative chemotherapy was not a common treatment regardless of the patients' BMI status. Preoperative chemotherapy was more frequently administered to premenopausal patients in all three BMI groups (P < 0.001 in patients with BMI < 25 kg/m2 and BMI 25.0 ≤ BMI < 30.0 kg/m2, and P = 0.01 in patients with BMI ≥ 30 kg/m2, respectively).
Table 2
comparative analysis of patient characteristics and menopausal status according body mass index (kg/m2 ) status of studied patients.
| BMI < 25 kg/m2 | 25.0 ≤ BMI < 30.0 kg/m2 | BMI ≥ 30 kg/m2 |
| Pre menopausal | Post menopausal | P-value | Pre menopausal | Post menopausal | Pvalue | Pre menopausal | Post menopausal | P-value |
Mean age (SD) | 47.57(8.27) | 66.12(9.36) | | 49.31(7.86) | 65.29(8.855) | | 50.62(7.56) | 64.67(8.28) | |
Surgery Type | | |
| | | < 0.001 | | | < 0.001* | | | 0.06 |
Quadrantectomy (BCS) | 664(57.7%) | 436 (49.1%) | 991 (61.4%) | 849 (58.2%) | 585 (61.4%) | 718 (62.7%) |
Mastectomy | 417 (36.1%) | 417 (46.9%) | 508 (31.4%) | 553 (37.9%) | 304 (31.9%) | 374 (32.6%) |
Quadrantectomy (BCS) ,then Mastectomy | 69 (6.0%) | 28 (3.1%) | 111 (6.9%) | 49 (3.4%) | 111 (6.9%) | 49 (3.4%) |
Stage |
1 | 242 (33.5%) | 158 (31.7%) | 0.16 | 313 (29.4%) | 267 (30.8%) | 0.17 | 192 (29.4%) | 184 (26.9%) | 0.51 |
2 | 427 (59.1%) | 288 (57.8%) | 655 (61.6%) | 503 (58.1%) | 392 (60.1%) | 420 (61.4%) |
3 | 53 (7.3%) | 52 (10.4%) | 95 (8.9%) | 96 (11.1%) | 68 (10.4%) | 80 (11.7%) |
Permanent Pathology Multifocal |
No | 1049 (91.2%) | 833 (94.6%) | 0.004 | 1479 (91.9%) | 1387 (95.7%) | < 0.001 | 867 (91.4%) | 1070 (94.1%) | 0.01 |
Yes | 101 (8.8%) | 48 (5.4%) | 867 (8.1%) | 1070 (4.3%) | 82 (8.6%) | 67 (5.9%) |
Permanent Pathology Tumor Grade |
1 | 174 (16.7%) | 184 (23.1%) | < 0.001 | 232 (15.7%) | 255 (19.5%) | 0.01 | 149 (17.3%) | 185 (17.8%) | 0.01 |
2 | 638 (61.3%) | 480 (60.2%) | 921 (62.5%) | 806 (61.7%) | 491 (57.0%) | 645 (62.2%) |
3 | 228 (21.9%) | 134 (16.8%) | 321 (21.8%) | 246 (18.8%) | 222 (25.8%) | 207 (20.0%) |
Invasion |
Non | 587) 51.0%( | 414)47.0%( | 0.06 | 756(47%) | 626(43.2) | 0.03 | 439(46.3%) | 499(43.9%) | 0.3 |
Vascular | 271)23.6%( | 217)24.6%( | 392 (24.3%) | 406 (28.0%) | 239 (25.2%) | 315 (27.7%) |
Preneural | 75)6.5%( | 76) 8.6%( | 120 (7.5%) | 110 (7.6%) | 68 (7.2%) | 80 (7.0%) |
Both of them | 178)15.5%( | 155) 17.6%( | 290(18.0%) | 278 (19.2% | 170 (17.9%) | 217 (19.1%) |
Lymphatic, Vascular | 39) 3.4%( | 19)2.2%( | 52 (3.2%) | 30 (2.1%) | 33 (3.5%) | 26 (2.3%) |
Axillary Type |
ALND at first | 488 (42.7%) | 403 (47.5%) | 0.07 | 660 (41.3%) | 678 (47.8%) | 0.002 | 381(40.5%) | 442(39.9%) | 0.56 |
SLNB | 458 (40.1%) | 323 (38.0%) | 682 (42.7%) | 543 (38.3%) | 151 (16.0%) | 162 (14.6%) |
SLNB then ALND | 197 (17.2%) | 123 (14.5%) | 255 (16.0%) | 198 (14.0%) | 409 (43.5%) | 503 (45.4%) |
Hormone receptor |
Luminal A | 564 (49.0%) | 406 (46.1%) | < 0.001 | 772 (48.0%) | 717 (49.4%) | < 0.001 | 449 (47.3%) | 579 (50.9%) | 0.007 |
Luminal B | 211 (18.3%) | 129 (14.6%) | 288 (17.9%) | 187 (12.9%) | 142 (15.0%) | 149 (13.1%) |
Her2 | 80 (7.0%) | 71 (8.1%) | 143 (8.9%) | 135 (9.3%) | 102 (10.7%) | 81 (7.1%) |
Triple Negative | 130 (11.3%) | 88 (10.0%) | 172 (10.7%) | 110 (7.6%) | 106 (11.2%) | 113 (9.9%) |
Preoperative Chemotherapy |
No | 892 (77.6%) | 753 (85.5%) | < 0.001 | 1300 (80.7%) | 1248 (86.1%) | < 0.001 | 776 (81.8%) | 976 (85.8%) | 0.01 |
Yes | 258 (22.4%) | 128 (14.5%) | 310 (19.3%) | 202 (13.9%) | 173 (18.2%) | 161 (14.2%) |
Postoperative Chemotherapy |
No | 154 (13.4%) | 152 (17.3%) | 0.01 | 185 (11.5%) | 228 (15.7%) | < 0.001 | 106 (11.2%) | 164 (14.4%) | 0.01 |
Yes | 996 (86.6%) | 729 (82.7%) | 1425 (88.5%) | 1222 (84.3%) | 843 (88.8%) | 973 (85.6%) |
Radiotherapy postoperative |
No | 324 (36.8%) | 204 (17.7%) | < 0.001 | 410 (28.3%) | 280 (17.4%) | < 0.001 | 272 (23.9%) | 162 (17.1%) | < 0.001 |
Yes | 557 (63.2%) | 946 (82.3%) | 1040 (71.7%0 | 1330 (82.6%) | 865 (76.1%) | 787 (82.9%) |
Hormone therapy |
No | 278(24.2%) | 211(24.0%) | 0.9 | 392(24.3%) | 328(22.6%) | 0.26 | 268(28.2%) | 261(23.0%) | 0.006 |
Yes | 872(75.8%) | 670(76.0%) | 1218(75.7%) | 1122(77.4%) | 681(71.8%) | 876(77.0%) |
Table 3 presents a summary of the 1-, 3-, and 5-year OS and DFS outcomes for different BMI categories across TNM stages. In stages 1 and 2, all three BMI groups showed OS rates above 99% at 1 and 3 years. Moreover, patients across all BMI categories in stages 1 and 2 exhibited OS rates exceeding 87% at 5 years (Figs. 1 and 2). The OS rates for BMI categories in TNM stages 1 and 2 did not show any statistically significant differences (P = 0.34 in TNM stage 1 and P = 0.98 in TNM stage 2).
Moving on to stage 3, all three BMI groups demonstrated OS rates surpassing 97% at 1 and 3 years among the studied patients. For patients in TNM stage 3, the OS rates were above 71% at 5 years (see Fig. 3). The OS outcomes for BMI categories in TNM stage 3 did not show statistically significant discrepancies (P = 0.33).
In stages 1 and 2, all three BMI groups displayed DFS rates exceeding 95% at 1 year. Additionally, the DFS rates were higher than 95% at 3 years for patients in TNM stages 1 and 2. Patients in TNM stages 1 and 2 showcased DFS rates above 81% at 5 years (Figs. 4 and 5). The DFS outcomes for BMI categories in TNM stages 1 and 2 did not demonstrate any statistically significant variances (P = 0.77 in TNM stage 1 and P = 0.11 in TNM stage 2).
Moving to stage 3, the three BMI groups exhibited DFS rates of 92%, 88%, and 92% at 1 year, respectively. These patients also displayed DFS rates ranging from 81–86% at 3 years (Fig. 6). The DFS rates were between 74–84% at 5 years. The DFS rates for BMI categories in TNM stage 3 did not show any statistically significant differences (P = 0.57).
Table 3
summarizes the 1-, 3-, and 5-year OS and DFS outcomes for BMI categories across TNM stage.
| Overall Survival times (%) | Disease Survival times (%) |
1 | 3 | 5 | P value* | 1 | 3 | 5 | P value* |
Stage1 |
BMI < 25 | 100 | 99 | 87 | 0.34 | 98 | 96 | 92 | 0.77 |
25.0 ≤ BMI < 30.0 | 100 | 99 | 93 | 97 | 95 | 91 |
BMI ≥ 30 | 99 | 99 | 93 | 97 | 95 | 92 |
Stage2 |
BMI < 25 | 100 | 99 | 87 | 0.98 | 95 | 92 | 88 | 0.11 |
25.0 ≤ BMI < 30.0 | 100 | 99 | 92 | 97 | 93 | 91 |
BMI ≥ 30 | 100 | 99 | 89 | 96 | 93 | 90 |
Stage3 |
BMI < 25 | 100 | 100 | 78 | 0.33 | 92 | 85 | 74 | 0.57 |
25.0 ≤ BMI < 30.0 | 99 | 97 | 71 | 88 | 81 | 78 |
BMI ≥ 30 | 100 | 97 | 77 | 92 | 86 | 84 |
* Wilcoxon (Gehan) test |
Table 4 provides a summary of the 1-, 3-, and 5-year OS and DFS outcomes for various BMI categories based on menopausal status in different TNM stages.
In stage 1, all three BMI groups showed OS rates above 99% at 1 and 3 years in premenopausal patients (Fig. 7). For post-menopausal patients, those with BMI < 25 kg/m2 and BMI 25.0 ≤ BMI < 30.0 kg/m2 categories displayed exceptional 100% OS rates at 1 and 3 years. Additionally, post-menopausal patients with BMI ≥ 30 kg/m2 exhibited OS rates of 99% and 98% at 1 and 3 years, respectively (Fig. 10). Irrespective of menopausal status, all patients across all BMI categories demonstrated OS rates of ≥ 85% at 5 years in TNM stage 1 (Figs. 7 and 10). The OS outcomes for BMI categories based on menopausal status in stage 1 did not show any statistically significant differences (P = 0.83 in premenopausal and P = 0.91 in postmenopausal women).
Moving to stage 2, patients in all BMI categories, regardless of menopausal status, exhibited OS rates above 98% for 1, 3, and 5 years. Notably, postmenopausal patients with BMI less than 25 kg/m2 exhibited OS rates of 85% at 5 years (Figs. 8 and 11). The OS outcomes for BMI categories based on menopausal status in stage 2 did not reveal any statistically significant variations (P = 0.43 in premenopausal women and P = 0.81 in postmenopausal women).
In TNM stage 3, premenopausal patients categorized as BMI < 25 displayed exceptional 100% OS rates over 1, 3, and 5 years. Patients in the other two BMI categories in the premenopausal group showed OS rates exceeding 97% at 1 and 3 years of follow-up. Moreover, premenopausal patients in the remaining two BMI categories demonstrated OS rates of 70% and 78% at the 5-year mark in stage 3 (Fig. 9). During this stage, all three BMI groups exhibited OS rates surpassing 97% at 1 and 3 years in post-menopausal patients. Post-menopausal patients in the BMI < 25 category showed a 63% OS rate at the 5-year mark. Additionally, post-menopausal patients in the other two BMI categories displayed OS rates of 80% and 79% at 5 years in stage 3, respectively (Fig. 12). The OS outcomes for BMI categories based on menopausal status in stage 2 did not yield statistically significant differences (P = 0.05 in premenopausal and P = 0.42 in postmenopausal women).
In stage 1, all three BMI groups exhibited DFS rates of 89% or higher for 1, 3, and 5 years, irrespective of menopausal status (Figs. 1 and 10). The DFS outcomes for BMI categories across menopausal status in TNM stage 1 did not show statistically significant differences (P = 0.31 in premenopausal women and P = 0.25 in postmenopausal women).
Moving to stage 2, all three BMI groups demonstrated DFS rates exceeding 90% for 1 and 3 years, regardless of menopausal status (Figs. 14 and 17). Premenopausal patients with a BMI between 25.0 ≤ BMI < 30.0 kg/m2 exhibited a 91% DFS rate over 5 years. Patients in the other two BMI categories achieved an 88% DFS rate over 5 years (Fig. 8). Postmenopausal patients with BMI between 25.0 ≤ BMI < 30.0 and BMI ≥ 30 categories showed 92% DFS rates over 5 years, while patients with a BMI > 25 kg/m2 had an 87% DFS rate over the same period (Fig. 17). Similar to stage 1, DFS outcomes for BMI categories across menopausal status in TNM stage 2 were not statistically significant (P = 0.35 in premenopausal women and P = 0.25 in postmenopausal women).
In stage 3, patients across all BMI categories, irrespective of menopausal status, exhibited DFS rates higher than 90% for 1 year. Notably, patients with a BMI of 25.0 ≤ BMI < 30.0 kg/m2 showed an 88% DFS rate in the first year, regardless of menopausal status. Furthermore, all three BMI categories displayed DFS rates exceeding 80% for 3 years, independent of menopausal status (Figs. 15 and 18). Specifically, premenopausal patients in the BMI ≥ 30 kg/m2 category showed an 81% DFS rate over 5 years. Patients in the other two BMI categories demonstrated DFS rates of 70% and 78% over 5 years in TNM stage 3 (Fig. 15). As in the previous stages, DFS outcomes for BMI categories across menopausal status in TNM stage 3 did not yield statistically significant differences (P = 0.82 in premenopausal women and P = 0.67 in postmenopausal women).
Table 4
Overall survival and Disease Survival rate for BMI categories across menopausal status in TNM stage
Overall Survival times (%) | Disease Survival times (%) |
Stage 1 |
| | 1 | 3 | 5 | P value* | 1 | 3 | 5 | P value* |
Pre-menopausal | BMI < 25 | 99 | 99 | 91 | 0.83 | 97 | 96 | 92 | 0.31 |
25.0 ≤ BMI < 30.0 | 100 | 99 | 95 | 96 | 93 | 89 |
BMI ≥ 30 | 100 | 99 | 90 | 97 | 96 | 94 |
Post-menopausal | BMI < 25 | 100 | 100 | 85 | 0.91 | 99 | 97 | 94 | 0.25 |
25.0 ≤ BMI < 30.0 | 100 | 100 | 91 | 98 | 97 | 94 |
BMI ≥ 30 | 99 | 98 | 96 | 96 | 95 | 90 |
Stage 2 |
Pre-menopausal | BMI < 25 | 100 | 98 | 88 | 0.43 | 96 | 92 | 88 | 0.35 |
25.0 ≤ BMI < 30.0 | 100 | 99 | 93 | 98 | 93 | 91 |
BMI ≥ 30 | 99 | 99 | 81 | 96 | 91 | 88 |
Post-menopausal | BMI < 25 | 100 | 100 | 85 | 0.81 | 94 | 91 | 87 | 0.09 |
25.0 ≤ BMI < 30.0 | 100 | 98 | 91 | 96 | 94 | 92 |
BMI ≥ 30 | 100 | 99 | 90 | 96 | 95 | 92 |
Stage 3 |
Pre-menopausal | BMI < 25 | 100 | 100 | 100 | 0.05 | 92 | 82 | 70 | 0.82 |
25.0 ≤ BMI < 30.0 | 98 | 97 | 70 | 88 | 82 | 78 |
BMI ≥ 30 | 100 | 97 | 78 | 91 | 85 | 81 |
Post-menopausal | BMI < 25 | 100 | 98 | 63 | 0.42 | 90 | 86 | 82 | 0.67 |
25.0 ≤ BMI < 30.0 | 99 | 98 | 80 | 88 | 81 | 80 |
BMI ≥ 30 | 100 | 97 | 79 | 92 | 87 | 85 |
* Wilcoxon (Gehan) test |