lymphovascular invasion (intralymphovascular tumor emboli) is closely related to the adverse outcome of many malignant tumors [16–18]. As a risk factor for recurrent breast cancer following modified radical mastectomy, lymphovascular tumor emboli, especially lymphatic tumor emboli, has been included in the St Gallen consensus for breast cancer . Karlsson et al’s  study results showed that the failure rate of chemotherapy in breast cancer patients detected with lymphovascular invasion was higher. Shen et al  showed that lymphovascular tumor emboli can promote local tumor recurrence and distant metastasis. Therefore, lymphovascular tumor emboli is a reliable indicator for the distant metastasis of breast cancer and the assessment of patients’ overall survival. We intended to predict the risk of lymphovascular invasion of the most common invasive ductal carcinoma using various imaging patterns of digital mammography, the most commonly used imaging tool.
From the data of this study group, there was no statistical significance of the differences in the age, childbearing history, miscarriage history, family history and other medical history between the LVI positive group and the LVI negative group. Nulliparity, miscarriage, and family history of breast cancer do not increase the LVI occurrence rate in breast cancer patients. First discovered in breast cancer and breast cells, CA153 is a tumor marker with relatively higher specificity for breast cancer diagnosis. With the advancing of breast cancer, the CA153 sensitivity increased from 66–80% . However, in this study group, there were only 4 (3.3%) CA153 positive cases. While no statistical significance was found in differences of ER, PR, Her-2, E-cad, and P53 between the LVI positive group and the LVI negative group, cases with high expression of Ki-67 (> 30%) in the LVI positive group were more than that in the LVI negative group, which was statistically significant (P = 0.012). Many literatures have also confirmed that Ki-67 is associated with tumor differentiation, lymphovascular invasion, metastasis, and recurrence [23–25].
The data of this study group showed that there is no difference in mammographic background presented by digital mammography and direct patterns of breast cancer, such as mammographic density, location of mass, number, size, shape, margin, boundary, calcification classification, etc., between LVI positive group and LVI negative group. Therefore, the above imaging patterns cannot be used to predict LVI occurrence. Also, heterogeneously dense and extremely dense breast do not increase the risk of LVI occurrence. However, the differences in indirect features such as interstitial edema and breast skin thickening between LVI positive group and LVI negative group were statistically significant (P = 0.013 and 0.000, respectively). In addition, multivariate analysis indicated that interstitial edema, blurring of subcutaneous fat layer, and skin thickening were independent risk factors for predicting LVI occurrence (P = 0.045, 0.017 and 0.001, respectively). In clinical work-up, physicians should be highly vigilant about LVI occurrence once the above three imaging patterns are found on digital mammography. Even if lymph node metastasis is negative in sentinel lymph node and axillary lymph node biopsies, possibility that breast cancer cells has infiltrated into surrounding vessels but not yet reached upwards to the axillary lymph nodes should be considered. Accordingly, adjustments in postoperative adjuvant therapy should be considered to reduce risk of recurrence and distant metastasis and thus improve patients’ survival time.
We have thought that the axillary lymph nodes shown on digital mammography could be used to predict LVI occurrence. However, this group of study data shows that there is no difference in the size and shape of axillary lymph nodes between the LVI positive group and the LVI negative group (P = 0.166), which might be explained by failure of displaying axillary lymph nodes on the digital mammography image. In addition, lymph node enlargement (> 1 cm) and a full shape does not always mean lymph node metastasis, it may also suggest lymphoid node reactive hyperplasia.
Nomogram is a statistical model used for individualized predictive analysis of clinical events. Compared with other predictive statistical methods, Nomogram analysis provides a better individualized prognostic risk assessment in an intuitive, visual way . This study also established a nomogram model for predicting the risk of LVI occurrence in individuals based on digital mammographic imaging patterns. For example, we can learn from Fig. 3 that, if the patient presents with interstitial edema, subcutaneous fat, and skin thickening, along with Ki-67 high expression, the score will be 95 + 100 + 87 + 48 = 330 points, with the corresponding risk of LVI being 68%. In this way, clinicians can better understand patients’ clinical prognosis, and develop a more effective and targeted therapeutic regime.