The association between use of long-acting, progestin-based contraceptives and risk of breast, gynaecological and other cancers: A population-based, nested case-control study using linked administrative data — ASN Events
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  3. The association between use of long-acting, progestin-based contraceptives and risk of breast, gynaecological and other cancers: A population-based, nested case-control study using linked administrative data

The association between use of long-acting, progestin-based contraceptives and risk of breast, gynaecological and other cancers: A population-based, nested case-control study using linked administrative data (#36)

Karen Tuesley 1 , Katrina Spilsbury 2 , Sallie Pearson 3 , Peter Donovan 4 , Andreas Obermair 5 , Michael Coory 6 , Sitwat Ali 7 , Nirmala Pandeya 7 , Louise Stewart 8 , Susan Jordan 1 , Penelope Webb 7
  1. School of Public Health, University of Queensland, Brisbane, QLD, Australia
  2. Institute for Health Research, The University of Notre Dame Australia, Fremantle, WA, Australia
  3. School of Population Health, University of New South Wales, Sydney, NSW, Australia
  4. Clinical Pharmacology Department, Royal Brisbane and Women's Hospital, Brisbane, QLD, Australia
  5. Queensland Centre for Gynaecological Cancer, Royal Brisbane and Women’s Hospital, Brisbane, QLD, Australia
  6. Mater Research Institute, University Of Queensland, Brisbane, QLD, Australia
  7. Population Health Department, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
  8. School of Population and Global Health, The University of Western Australia, Perth, Western Australia, Australia

Background: Use of long-acting, reversible contraceptives has increased substantially over the last 20 years, however there is limited understanding on how these might influence cancer risk.

Methods: We conducted a nested case-control study among a national cohort of Australian women (176,601 women with a first cancer diagnosis 2004-2013 and 882,999 matched controls) to investigate the associations between the levonorgestrel intrauterine system (LNG-IUS), etonogestrel implants (ENG-IMP) and depot-medroxyprogesterone acetate (DMPA) and cancer risk and compared these results to the oral contraceptive pill. We used conditional logistic regression to estimate odds ratios (OR) and 95% confidence intervals (CI).

Findings: Compared to never users, use of LNG-IUS, ENG-IMP and DMPA was associated with 16%, 8% and 11% increased risks, respectively, of developing cancer. For LNG-IUS and DMPA this persisted among former users, while for ENG-IMP the risk returned to baseline after cessation, similar to the oral contraceptive pill. LNG-IUS and ENG-IMP use was associated with an increased risk of breast cancer (OR=1·26, 95%CI:1·21-1·31 and OR=1·24, 95%CI:1·17-1·32, respectively), but not DMPA except when used for five or more years (OR=1·23, 95%CI:0·95-1·59). Use of LNG-IUS (1+ years) was associated with reduced risks of endometrial (OR=0·80, 95%CI:0·65-0·99), ovarian (OR=0·71, 95%CI:0·57-0·88) and cervical cancers (OR=0·62, 95%CI:0·51-0·75). ENG-IMP and DMPA were associated with reduced risk of endometrial (OR=0·21, 95%CI:0·13-0·34; OR=0·52, 95%CI:0·32-0·84) and, less strongly, ovarian cancer (OR=0·76, 95%CI:0·57-1·02; OR=0·82, 95%CI:0·54-1·25).

Interpretation: LARCs have similar cancer associations to the oral contraceptive pill (reduced endometrial and ovarian cancer risks and short-term increased breast cancer risk). Women should be advised of this when choosing a form of contraception.

* SJ & PW are joint senior authors.

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