Immunohistochemistry can be redone after breast cancer treatment. After breast cancer treatment, there will be a follow-up treatment, which needs to redo immunohistochemistry for the testing of estrogen receptor, progesterone receptor and sensitivity to targeted drug therapy and other related indexes, to assess the severity of breast cancer after treatment and to formulate the next treatment plan. Therefore, redoing immunohistochemistry after breast cancer treatment is of guiding significance for subsequent treatment. Redoing immunohistochemistry after breast cancer treatment can guide the direction of treatment and clarify the treatment plan in order to achieve better treatment results. Even if immunohistochemistry has been done once and confirmed as breast cancer, patients have to combine with the doctor’s guidance and advice after surgery and actively cooperate with the follow-up examination and treatment to inhibit the further spread of cancer cells, control the progression of the disease as far as possible and prolong the survival period.