Table 5.

Multivariate regression analysis factors influencing the likelihood of undergoing mastectomy compared BCT

Parameter	Estimate (β)	OR (95% CI)	Standard error	Z value	p value
SES (per 10% stratum)	− 0.023	0.98 (0.97–0.98)	0.003	− 9.013	< 0.001
Age (years)	0.004	1.00 (1.00–1.01)	0.001	7.758	< 0.001
Year of surgery	− 0.073	0.93 (0.92–0.94)	0.003	− 22.659	< 0.001
Hospital volume
Small volume	NA	1.00 (reference)	NA	NA	NA
Average volume	0.009	1.01 (0.96–1.06)	0.027	0.323	0.747
Large volume	− 0.111	0.90 (0.85–0.94)	0.025	− 4.415	< 0.001
Tumor grade
Low grade	NA	1.00 (reference)	NA	NA	NA
Intermediate grade	0.190	1.21 (1.16–1.26)	0.019	9.885	< 0.001
High grade	0.270	1.31 (1.25–1.37)	0.023	11.649	< 0.001
Histological subtype
Ductal carcinoma	NA	1.00 (reference)	NA	NA	NA
ILC	0.625	1.87 (1.79–1.95)	0.022	28.307	< 0.001
Both	0.836	2.31 (2.13–2.49)	0.039	21.172	< 0.001
Mucinous	0.07	1.07 (0.96–1.19)	0.055	1.271	0.204
Medullary	− 0.055	0.95 (0.79–1.14)	0.093	− 0.588	0.556
Tubular	− 0.193	0.82 (0.69–0.99)	0.093	− 2.083	0.037
Other	0.271	1.31 (1.16–1.49)	0.064	4.217	< 0.001
Hormone receptor status
Her2 receptor negative	− 0.128	0.88 (0.83–0.93)	0.027	− 4.775	< 0.001
Progesterone receptor positive	0.019	1.02 (0.98–1.06)	0.020	0.928	0.353
Estrogen receptor positive	0.002	1.00 (0.95–1.06)	0.028	0.058	0.954
Triple negative	0.171	1.19 (1.08–1.30)	0.047	3.614	< 0.001
Patient medical history
History of disease	NA	1.00 (reference)	NA	NA	NA
Non-oncological medical history	0.258	1.29 (1.23–1.37)	0.028	9.339	< 0.001
Oncological medical history	1.612	5.01 (4.01–6.26)	0.114	14.198	< 0.001
Tumor stage
Stage I tumor	NA	1.00 (reference)	NA	NA	NA
Stage II tumor	1.231	3.42 (3.33–3.53)	0.015	82.180	< 0.001

NA not applicable, OR odds ratio, CI confidence interval, SES socioeconomic status, ILC invasive lobular carcinoma