A randomised double-blinded study, in which the patients either get methylprednisoloneacetate or saline solution in the mastectomy cavity to evaluate the efficacy of methylprednisoloneacetate in preventing seroma in patients operated for primary breast cancer.

After mastectomy, up to 90 % of patients develops seroma in the cavity. The treatment is puncture, which is a small operation, but many patients have to come several times, and there is a risk of infection. In some cases further treatment can be postponed.

Preventing seroma to develop would be an improvement in the treatment of breast cancer patients operated with mastectomy.

An earlier study found that the seroma production was significant lower in the group who had Prednison injected directly into the cavity.

In this study the patient are divided into two groups: patients who have mastectomy and axillary dissection and patients who have mastectomy and Sentinel Node operation. Each group are examined separately.

Using Prednison in patients after operation could be a potential risk, but correct injection into the cavity will seldom give systemic side effects.

Inclusion Criteria:

• women with primary breast cancer or Ductal carcinoma in situ, mastectomy plus either Sentinel Node or Axillary dissection, signed consent form

Exclusion Criteria:

• dissection of the axilla in les than 4 month, treatment with steroids, pregnancy, if the patient don't speak danish, allergy towards steroid, other medical conditions which the investigator find contradict participating

Patients operated for primary breast cancer with mastectomy and eihter axillary dissection or Sentinel Node operation