Effect of Endocrine Therapy Duration on Clinical Outcome of Patients With HR+ Intraductal Carcinoma of the Breast

This study will investigate the relationship between the endocrine therapy and the survival of patients with hormone receptor positive intraductal carcinoma of the breast, and the optimal duration of medication. This study will also analyze the risk factors of recurrence and metastasis of hormone receptor positive intraductal carcinoma of the breast and establish a prognosis model to further clarify the specific reasons for recurrence and metastasis, adverse reactions, and drug withdrawal in patients with hormone receptor positive intraductal carcinoma of the breast after endocrine therapy.

Intraductal carcinoma of the breast accounts for 20% of newly diagnosed breast cancer. In addition to necessary surgical treatment, 5-year endocrine therapy is also essential for patients with hormone receptor positive ductal carcinoma of the breast. Commonly used drugs include selective estrogen receptor modulators (Tamoxifen, Toremifene) and aromatase inhibitors (Exemestane, Anastrozole, Letrozole). Although these drugs can effectively reduce the recurrence and metastasis of ductal carcinoma of the breast, the adverse reactions of the above drugs significantly reduce the quality of life and treatment compliance of the patients. Therefore, the choice of endocrine therapy for intraductal carcinoma of the breast has been widely discussed. Is it possible for de-escalation of endocrine treatment intensity to reduce adverse reactions and improve patient compliance? Recently, a phase 3 clinical trial found that compared with placebo group, the adverse reactions of Tamoxifen group treated with 5 mg/d (conventional dose 20 mg/d) Tamoxifen for 3 years had less adverse reactions and achieved significant efficacy. This study revealed the reliable efficacy and safety of Tamoxifen, a low-dose drug for treatment of hormone receptor positive intraductal carcinoma of the breast. However, little is reported on the reasonable duration of Aromatase inhibitors for endocrine therapy in patients with intraductal carcinoma of the breast.

This study will investigate the relationship between the endocrine therapy and the survival of patients with hormone receptor positive intraductal carcinoma of the breast, and the optimal duration of medication. This study will also analyze the risk factors of recurrence and metastasis of hormone receptor positive intraductal carcinoma of the breast and establish a prognosis model to further clarify the specific reasons for recurrence and metastasis, adverse reactions, and drug withdrawal in patients with hormone receptor positive intraductal carcinoma of the breast after endocrine therapy.

Eligibility Criteria:
Inclusion Criteria:

* (1)Female patients aged ≥ 18 years and ≤ 85 years
* (2)The primary lesions and lymph nodes of the breast must meet all of the following conditions:

  1. Histologically confirmed intraductal carcinoma of the breast, accompanied by microinvasion, with the infiltration range ≤ 1 mm;
  2. Have received radical resection or breast conserving surgery;
  3. Patients who have received breast conserving surgery must undergo pathological examination to confirm there is no residual cancer tissue on the cutting edge and receive postoperative radiotherapy within the prescribed dose and range;
  4. No lymph node metastasis (including micrometastasis) is detected by postoperative pathological examination;
  5. Immuno
  6. Immunohistochemical staining results are positive for estrogen receptor (ER) or progesterone receptor (PR), which is defined as ER or PR immunoreactivity intensity ≥1+ or expression percentage ≥ 1%.
* (3)A volunteer to participate in the study and willing to cooperate with follow-up

Exclusion Criteria:

* (1)Patients with newly diagnosed metastatic breast cancer or other malignant tumors without breast intraductal carcinoma;
* (2) Patients who have other malignant tumors before the initial diagnosis of intraductal carcinoma of the breast
* (3) Patients who have received endocrine therapy with drugs including Toremifene, Tamoxifen, Anastrozole, Letrozole or Exemestane before the initial diagnosis of intraductal carcinoma of the breast
* (4) Patients who have a serious comorbidity or other comorbidities that interfere with the conduct of the study, or those who are considered not suitable for participation in this study