Table 2.

A logistic model predicting the type of surgical procedure (N = 4238).

Surgical procedure	Treatment sequence	OR (95% CI)	P-value
Subcutaneous/simple mastectomy	Systemic therapy after surgery	1 [Reference]	<0.001
	Systemic therapy before surgery	2.32 (1.97–2.74)
Modified radical mastectomy	Systemic therapy after surgery	1 [Reference]	<0.001
	Systemic therapy before surgery	2.23 (1.90–2.63)
(Extended) radical mastectomy	Systemic therapy after surgery	1 [Reference]	<0.001
	Systemic therapy before surgery	2.27 (2.22–2.31)

Only patients who underwent combined treatment with systemic therapy and surgery of the primary site were included in this model. The logistic regression model was adjusted for year of diagnosis, age, grade, T category, N category, and number of sites of metastasis. The variables above were selected using the stepwise AIC method in both directions. The reference category of surgical procedure is partial mastectomy. Abbreviations: OR, odds ratio; CI, confidence interval.