DCIS Permanent Breast Seed Implant

Official Title

A Phase II Study of adjuvant Permanent Breast Seed Implant (PBSI) for Ductal Carcinoma In Situ (DCIS).


Each year in North America 60,000 women are diagnosed with a pre-cancerous breast disease called Ductal Carcinoma in Situ (DCIS). Without treatment this disease might transform into a deadly cancer, so patients undergo a surgery removing the lump, followed by 25 daily radiation treatments. This radiation treatment induces frequently painful skin blistering, and can sometime induce heart failure and secondary cancer in the long term.

Our team has pioneered a new therapy realizing the permanent implantation of tiny radioactive seeds into the surgical cavity to replace the 25 radiation treatment. The procedure is realized in a single one hour procedure under light anesthesia. The seeds deliver the radiation treatment while the patient lives a normal life. We have already reported its efficiency and tolerance on infiltrating cancer. This new study will offer to volunteer patients the seed treatment after they have their DCIS surgically removed. The study will evaluate if the technique is efficient to prevent DCIS recurrence after surgery.

Trial Description

Primary Outcome:

  •  Rate of ipsilateral breast local recurrence, invasive or in-situ.

Secondary Outcome:

  • Breast cancer mortality and survical;
  • Quality Assurance of the treatment comparing two Ontario centres.

With the generalization of mammography screening 20~30% of new breast cancers are diagnosed at a pre-invasive stage named Ductal Carcinoma In-Situ (DCIS). This pre-cancer has a very good prognosis with a survival over 96% after breast conserving therapy involving a lumpectomy followed daily radiation treatments over 5 weeks.

Radiation therapy prevents breast recurrence, however it induces skin burns and it is disruptive for the patient life. A way to reduce the treatment burden is to use partial breast radiation that limits the amount of breast tissue irradiated and can be delivered faster. Our team has pioneered a Permanent Breast Seed Implant (PBSI) technique that is realized in a single one-hour session under light anesthesia.


  • To evaluate the efficiency of BPSI after breast conserving surgery for DCIS;
  • Compare the 2 months post-implant Quality Assurance between centres.


A prospective phase II clinical trial is proposed. Patients ≥ 50 years treated by breast conserving surgery for a single focus of pure DCIS ≤ 3 cm in diameter, resection margins >3mm, will be offered to receive PBSI instead of external beam radiation therapy in two institution in Ontario. We hypothesize that the local recurrence rate for low and intermediate risk DCIS will be 10% at 5 years with a confidence interval of ± 5%. A total of 115 patients are necessary to test this hypothesis. Patients will be clinically and mammographically followed up to 10 years to assess breast recurrences.


The potential risks includes an increase rate of local recurrence as it is not know if PBSI is as efficient as whole breast external radiation therapy for DCIS.

The potential benefits include:

  • The reduction of acute and permanent skin side effects like telangiectasia;
  • The reduction of the treatment time commitment.


Reviewed by OCREB.

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Canadian Cancer Society

These resources are provided in partnership with the Canadian Cancer Society