Magseed for locating impalpable breast cancer lesions

Study size, design and location

A national prospective audit of 1,183 patients from 42 units who had breast localisation procedures in the UK.

Intervention and comparator

Magseed compared with wire guided localisation procedures.

Key outcomes

There were 62% of people who had invasive cancer, 18.9% who had ductal carcinoma in situ, 12.6% mixed; and 6.4% were classed as other. Localisation methods were 33.5% Magseed guided (n=396) and 66.5% were wire guided (n=787). Bilateral localisation procedures were done in only 1.4% of cases. Of the 78 people with multifocal lesions, 10 people had 2 Magseeds and 1 person had Magseed plus wire. The was no index lesion in the excision specimen in 8 cases, of which only 1 was a localisation failure. In people with invasive or non-invasive disease, the re-excision rate for Magseed was 12.1%, and for wire guided excision was 14.8% (p=0.406). There was no significant difference (p>0.1) in all complications between the 2 localisation methods.

Strengths and limitations

The study was designed as an audit. Strengths and limitations were not assessed because limited information was reported in the abstract.

Study size, design and location

A service evaluation comparing the standard practice of guide wires with Magseed for lesion localisation in people having surgery to remove impalpable disease at a single institution in the UK.

Intervention and comparator

Magseed (n=128) compared with wire guided localisation (n=168).

Key outcomes

The study included 2 consecutive cohorts of people who had wire guided localisation or Magseed. The accuracy of the wire and seed placement (within 5 mm of the lesion) was 96% and 98%, respectively. In 1 person who had the Magseed procedure, the marker was placed more than 10 mm from the lesion and a wire was then placed to mark the correct site. Surgical excision was 97% with a wire and 95% with Magseed. No complications were reported with the wire or the Magseed.

Radiology and surgical staff reported statistically greater satisfaction with the Magseed localisation compared with the wire procedure. People felt less anxious using Magseed compared with wire (p=0.009). There was no difference in pain associated with the localisation procedure.

Strengths and limitations

This is a single-centre study. There is selection bias because Magseed should only be used for bracketing lesions that are more than 2 cm apart. There is recall bias based on self-reported data.

Study size, design and location

A prospective, open-label, single-arm phase 4 study of 107 people who had Magseed-localised breast conserving surgery at a single institution in the US.

Intervention and comparator

Magseed localisation procedure. No comparator.

Key outcomes

A total of 124 Magseeds placed; 93 people had 1 Magseed placed, 11 people had 2 Magseeds placed, and 3 people had 3 Magseeds placed. Radiographic breast lesions localised with the Magseed included masses (63%), calcifications (24%), architectural distortion (7%), and other lesions such as asymmetry. All Magseeds were placed less than 10 mm from the target lesion with 95% within 5 mm. There was a 100% Magseed retrieval rate with surgical excision, with the Magseeds retrieved in the initial resected specimen in all cases including those with more than 1 seed placed. Of the 98 malignant breast lesions, 9 cases (9.2%) had positive margins and 7 had a second procedure for margin re-excision. There were no adverse events associated with Magseed.

Strengths and limitations

No patients were lost to follow up. This was an open-label single-arm study without a direct comparison with other breast localisation techniques. Patients were recruited from 1 institution.

Study size, design and location

A prospective, single-arm, multicentre clinical audit in the UK of 137 people who had Magseed localisation for breast surgery.

Intervention and comparator

Magseed was used in the intervention group. No comparator.

Key outcomes

A total of 137 people had Magseed localisation with a total of 139 seeds. There were 16 people who had a diagnostic procedure and 121 who had therapeutic surgery. Most seeds were placed under ultrasound guidance (n=112) and 25 lesions were targeted under stereo guidance. The re-excision rate was 14.8% (n=18). All these re-excisions were carried out for ductal carcinoma in situ with or without an invasive component.

Strengths and limitations

This is a single-arm study. There was potential selection bias because people were allocated for Magseed localisation depending on service convenience.

Study size, design and location

A multicentre prospective non-randomised control trial done in the UK of 200 people having Magseed localisation or wire guided localisation.

Intervention and comparator

Magseed localisation was used in the intervention group (n=104). The comparator was wire guided localisation (n=96).

Key outcomes

Magseed localisation was planned for 104 people. A total of 4 people had wire guided localisation instead, including 2 people who had Magseed deployed at a distance from the target lesion and placement of a second Magseed was not feasible. Also, there were 2 people whose Magseeds were not localised using the Sentimag. Intraoperative identification and excision of the localised lesion was successful in 100% of people in both groups. There were no significant differences in the proportion of people who needed re-excision between the 2 groups (16% in Magseed and 14% using wire guided localisation, p=0.692). There was 1 person in the Magseed cohort who developed a haematoma after localisation and the seed was dislodged and contained within the haematoma. In a second patient with a lesion located next to the skin the Magseed was dislodged during dissection.

Strengths and limitations

This is non-randomised study, and there is potential selection bias in patient selection.