Objective  To analyze the treatment effect of the number of bortezomib, cyclophosphamide, and dexamethasone (BCD) chemotherapy courses for newly diagnosed multiple myeloma.

  Methods  We retrospectively analyzed data of patients with newly diagnosed multiple myeloma from January 2014 to July 2016 in Peking University People's Hospital. All 70 patients received two or more courses of BCD chemotherapy. Patients with extramedullary disease or amyloidosis were excluded. Patients completed their follow-up, and the treatment effects were studied in those who only received two, four, and six chemotherapy courses.

  Results  Among the 70 patients, the ratio of male to female was 36 :34, the median age of disease onset was 58.4 y (range: 33-81 y), and the number of patients with ISS stages Ⅰ, Ⅱ, and Ⅲ was 16, 18, and 36, respectively. The number of patients who received two, four, and six chemotherapy courses was 14, 20, and 36, respectively. The percentages of complete remission, equal or more than very good partial remission, equal or more than partial remission for patients who received two courses were 14.28%, 42.86%, and 71.42%, those for four courses were 30.00%, 60.00%, 80.00%, and those for six courses were 38.89%, 75.00%, 83.33%, respectively. During the median 15.37 (range: 2-32) months follow up, the estimated progression free survival (PFS) was 21.96 months (95% CI: 19.26-24.70). No statistically significant difference for PFS was observed among the three groups (P=0.700).

  Conclusions  For the BCD chemotherapy regimen, the maximum therapeutic effect occurred after four or more courses. As the number of induction courses after four chemotherapies increased, the depth of disease relief increased but overall remission did not show substantial improvement. Therefore, four or more BCD chemotherapies can be used for the first line of induction therapy.