[Levonorgestrel-releasing intrauterine device (Mirena) and breast cancer: what do we learn from literature for clinical practice?]

[Focus on intrauterine contraception in 15 questions and answers]

In recent years, intrauterine contraception has experienced a revival, explainable as much by the broadening of its indications as by the ever increasing demand, expressed by women, for a contraceptive method that is both reliable and not binding. In this review, we establish an up-to-date and comprehensive state of intrauterine contraception in 2010, by responding to key-questions, which arise from everyday practice in gynaecology.

Uterine perforation with the levonorgestrel-releasing intrauterine device: analysis of reports from four national pharmacovigilance centres

BACKGROUND

Levonorgestrel-releasing intrauterine devices (LNG-IUD) are commonly used for contraception and other indications in many countries. National pharmacovigilance centres have been receiving reports from healthcare professionals and patients of uterine perforation associated with the use of these LNG-IUDs.

METHODS

National pharmacovigilance centres in the Netherlands, New Zealand, Switzerland and Germany did a search on their adverse drug reaction databases for reports of cases of uterine perforation after insertion of a LNG-IUD received between the introduction of the LNG-IUD onto the market in the late 1990s and 15 July 2007. The number of women affected and patient characteristics such as age, parity and breastfeeding status were examined. In addition, the method of detection of the perforation and the time until discovery of the perforation were analysed.

RESULTS

Between the introduction of the LNG-IUD onto the market in each country and 15 July 2007, 701 cases of uterine perforation with a LNG-IUD were reported; 8.5% of the perforations were detected at the time of insertion. Abdominal pain and control/check-up visits were the most common events that lead to the detection of a perforation. Of 462 women known to be parous, 192 (42%) were breastfeeding at the time the perforation was discovered.

CONCLUSIONS

Uterine perforations can be asymptomatic and may remain undetected for a long time after IUD insertion. Abdominal pain, control/check-up visits or changes in bleeding patterns are triggers for detection of perforation and should therefore be taken seriously.

Use of the levonorgestrel-releasing intrauterine system in breast cancer patients

OBJECTIVE

To study the recurrence of breast cancer among patients who were using the levonorgestrel-releasing intrauterine system (LNG IUS).

DESIGN

A retrospective, controlled cohort analysis.

SETTING

Six Belgian hospitals.

PATIENT(S)

We identified 79 breast cancer patients who used the LNG IUS, and we selected a control group of 120 patients with no history of LNG IUS use and who were closely matched for age at diagnosis, tumor stage, tumor grade, and treatment modalities. Two subgroups were identified: [1] breast cancer patients who continued using the LNG IUS after diagnosis and [2] breast cancer patients who began using an LNG IUS after treatment for breast cancer.

INTERVENTION(S)

Patient's data were collected and survival analysis was performed.

MAIN OUTCOME MEASURE(S)

Breast cancer recurrence rate.

RESULT(S)

There was a recurrence rate of 21.5% (17/79) among LNG IUS users and of 16.6% (20/120) among the control group (adjusted hazard ratio, 1.86; 95% confidence interval, 0.86-4.00; no statistically significant difference). Subgroup analysis showed that women using the LNG IUS (n = 38) at the time of breast cancer diagnosis (and who continued its use) had a statistically significantly increased risk of recurrence (adjusted hazard ratio, 3.39; 95% confidence interval, 1.01-11.35) compared with patients in the control group. There was 47.4% (18/38) nodal involvement in this subgroup, and all patients who recurred had metastatic disease.

CONCLUSION(S)

Overall, we did not find an increased risk of breast cancer recurrence associated with use of the LNG-IUS. However, in a subgroup analysis of women who developed breast cancer while using an LNG IUS and who continued to use the LNG IUS, we found a higher risk of recurrence of borderline statistical significance. Additional research is needed to confirm or refute these findings.