Table 1 Characteristics of the studies included in the meta-analysis
From: Prognosis of pregnancy-associated breast cancer: a meta-analysis
Study ID | Country | No. of PABC cases | No. of controls | PABC definition | Cancer stage or grade | Mean/median age of PABC | Follow-up years | Outcomes measured | HR estimate | HR | 95% CI | NOS score | Matching criteria | Adjusting variable |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Mausner, 1969 [22] | USA | 73 | 647 | Pregnancy & < 6 months postpartum | Stage I II III, Grade I II III | 35 | 5 | OS | indirect | 1.36 | 1.07–1.73 | 7 | – | – |
Wallgren, 1977 [23] | Sweden | 15 | 58 | Pregnancy & < 12 months postpartum | Grade I II III | < 30 | 10 | OS | indirect | 1.35 | 0.71–2.58 | 7 | – | – |
Nugent, 1985 [24] | USA | 19 | 155 | Pregnancy | Stage I II III | 32 | 5 | OS | indirect | 0.96 | 0.55–1.67 | 6 | – | – |
Tretli, 1988-Pregnancy [25] | Norway | 20 | 40 | Pregnancy | Stage I II III | 33 | 4 | OS | indirect | 2.41 | 1.32–4.37 | 6 | Diagnosed year, diagnosed age | – |
Tretli, 1988-Postpartum [25] | Norway | 15 | 40 | Unspecified | Stage I II III | 36 | 4 | OS | indirect | 1.47 | 0.66–3.27 | 6 | – | |
Greene, 1988 [26] | USA | 8 | 36 | Pregnancy | NA | <35 | 14 | OS | indirect | 1.50 | 0.18–12.62 | 6 | – | – |
Petrek, 1991 [27] | USA | 56 | 166 | Pregnancy & < 12 months postpartum | NA | – | 5 | OS | paper | 0.74 | 0.37–1.45 | 6 | – | Node status |
Zemlickis, 1992 [28] | Canada | 102 | 269 | Pregnancy & postpartum (unspecified) | Stage 0 I II III IV | 33 | 25 | CSS | indirect | 1.25 | 0.93–1.69 | 8 | Stage, age at diagnosis | – |
Ishida, 1992 [29] | Japan | 192 | 191 | Pregnancy & < 24 months postpartum | Stage 0 Tis I II III IV | 32 | 10 | OS | indirect | 2.00 | 1.27–3.16 | 6 | – |  |
Guinee, 1994-Pregnancy [30] | USA | 26 | 139 | Pregnancy | NA | 28(20–29) | 10 | OS | paper | 2.83 | 1.24–6.45 | 8 | – | Tumour size, number of positive axillary nodes |
Guinee, 1994-Postpartum [30] | USA | 40 | 139 | < 12 Months postpartum | NA | 28(20–29) | 10 | OS | paper | 1.88 | 0.88–3.98 | 8 | – | |
Von Schoultz, 1995 [31] | Sweden | 173 | 1740 | Pregnancy & < 60 months postpartum | NA | < 50 | 7 | DFS | paper | 1.02 | 0.72–1.43 | 9 | – | Age, nodal status, tumour size, ER status |
Ezzat, 1996-OS [32] | Saudi Arabia | 28 | 84 | Pregnancy | Stage I II III | 20–45 | 7 | OS | paper | 0.90 | 0.6–1.3 | 6 | Year of diagnosis, date of beginning | – |
Ezzat, 1996-DFS [32] | Saudi Arabia | 28 | 84 | Pregnancy | Stage I II III | 20–45 | 7 | DFS | paper | 1.10 | 0.8–1.5 | 6 | – | |
Anderson, 1996-OS [33] | USA | 22 | 205 | Pregnancy & < 12 months postpartum | Stage 0 I II IIIa | < 30 | 10 | OS | paper | 2.40 | 1.28–4.50 | 8 | – | Stage, axillary LN involvement, adjuvant CT, tumour size |
Anderson, 1996-DFS [33] | USA | 22 | 205 | Stage 0 I II IIIa | < 30 | 10 | DFS | indirect | 3.19 | 1.20–8.49 | 8 | – | ||
Bonnier, 1997-OS [34] | France | 154 | 308 | Pregnancy & < 6 months postpartum | Grade I II III | 33.9(23.2–46.4) | 5 | OS | paper | 1.46 | 0.72–2.96 | 6 | – | Clinical tumour size, microscopic lymph-node involvement, inflammatory cancer, age |
Bonnier, 1997-DFS [34] | France | 154 | 308 | Grade I II III | 5 | DFS | paper | 1.48 | 1.00–2.19 | 6 | – | |||
Olson, 1998 [35] | USA | 146 | – | – | NA | < 45 | 15 | OS | paper | – | – | 7 | – | Age, tumour size, lymph nodes, ER status, histology |
Reeves, 2000 [36] | UK | – | – | – | Stage I II III IV | < 60 | > 10 | OS | paper | – | – | 9 | – | Age at diagnosis, year of diagnosis, hospital, weight in kg |
Ibrahim, 2000 [37] | Saudi Arabia | 72 | 216 | Pregnancy | Stage I II III IV, Grade I II III | 34 | 10 | OS | indirect | 0.94 | 0.62–1.44 | 6 | Age, stage, year of diagnosis | – |
Daling, 2002 [38] | USA | 83 | 309 | < 24 Months postpartum | Stage I II III IV | < 45 | 5 | OS | indirect | 2.30 | 1.4–3.9 | 9 | – | Age, diagnosis year |
Aziz, 2003 [39] | Pakistan | 24 | 48 | Pregnancy & < 12 months postpartum | NA | 32(20–45) | 7 | OS | indirect | 1.67 | 0.82–3.41 | 6 | Age, tumour grade, tumour size, axillary lymph node status | – |
Siegelmann-Danieli, 2003-OS [40] | Israel | 22 | 192 | Pregnancy & < 12 months postpartum | NA | 33(25–27) | 5 | OS | indirect | 3.39 | 0.58–19.81 | 6 | – | – |
Siegelmann-Danieli, 2003-DFS [40] | Israel | 20 | 181 | NA | 33(25–28) | 5 | DFS | indirect | 4.81 | 1.46–15.9 | 6 | – | – | |
Bladstrom, 2003 [41] | Sweden | 94 | 14,599 | Pregnancy | NA | ≤45 | 5 | OS | paper | 2.40 | 2.0–2.9 | 9 | – | Age, time of diagnosis, time period interaction, number of children, age at first child’s birth |
Bladstrom, 2003(2) [41] | Sweden | 94 | 14,599 | Pregnancy | NA | ≤45 | 10 | OS | paper | 1.20 | 0.9–1.7 | 9 | – | |
Whiteman, 2004 [42] | USA | 59 | 355 | < 12 Months postpartum | NA | 20–45 | 15 | OS | paper | 1.51 | 1.02–2.23 | 9 | – | Surgery, radiation therapy, race, oral contraceptive use, education, BMI, stage history of breast disease |
Rodriguez, 2008 [43] | USA | 797 | 4177 | Pregnancy & < 12 months postpartum | Stage I II III IV | < 55 | 13 | OS | paper | 1.14 | 1.00–1.29 | 9 | – | Race, tumour size, AJCC stage, surgery, hormone receptor |
Stensheim, 2009-Pregnancy [44] | Norway | 59 | 13,106 | Pregnancy | NA | < 50 | 5 | CSS | paper | 1.23 | 0.82–1.81 | 7 | – | Age, diagnostic period, initial extent of disease |
Stensheim, 2009-Postpartum [44] | Norway | 46 | 13,106 | < 6 Months postpartum | NA | < 50 | 5 | CSS | paper | 1.95 | 1.36–2.78 | 7 | – | |
Beadle, 2009-OS [45] | USA | 104 | 564 | Pregnancy & < 12 months postpartum | Stage I II III | ≤35 | 10 | OS | indirect | 1.24 | 0.87–1.79 | 6 | – | – |
Beadle, 2009-DFS (distant metastasis) [45] | USA | 104 | 564 | Pregnancy & < 12 months postpartum | Stage I II III | ≤35 | 10 | DFS | indirect | 1.35 | 0.98–1.85 | 6 | – | – |
Beadle, 2009-DFS (locoregional recurrence) [45] | USA | 104 | 564 | Stage I II III | ≤35 | 10 | DFS | indirect | 1.44 | 0.78–2.66 | 6 | – | – | |
Halaska, 2009-OS [46] | Greece | 32 | 32 | Pregnancy & < 12 months postpartum | Grade I II III | < 45 | 10 | OS | indirect | 1.42 | 0.58–3.48 | 6 | Age at diagnosis, tumour size, axillary lymph node status, presence or absence of metastatic deposits | – |
Halaska, 2009-DFS [46] | Greece | 32 | 32 | Grade I II III | < 45 | 10 | DFS | indirect | 1.82 | 0.82–4.05 | 6 | – | ||
Largillier, 2009-OS [47] | France | 105 | 788 | Pregnancy & < 12 months postpartum | Grade I II III | <35 | 10 | OS | paper | 1.51 | 1.05–2.20 | 7 | – | – |
Largillier, 2009-DFS [47] | France | 105 | 788 | Grade I II III | <35 | 10 | DFS | paper | 1.25 | 0.90–1.74 | 7 | – | – | |
Phillips, 2009 [48] | Multicentre | 676 | – | – | NA | – | 10 | OS | paper | – | – | 8 | – | Study centre, education, BMI, time since last full-term pregnancy, age at diagnosis |
Moreira, 2010 [49] | Brazil | 87 | 252 | Pregnancy & < 12 months postpartum | NA | ≤ 45 | 10 | OS | paper | 1.52 | 1.10–2.10 | 7 | Registration institution, age, registration year | – |
Johansson, 2011 [50] | Sweden | 1110 | 14,611 | Pregnancy & < 24 months postpartum | NA | 15–44 | 15 | OS | paper | 1.51 | 1.36–1.68 | 7 | – | Age, calendar time, education |
Murphy, 2012 [51] | USA | 99 | 186 | Pregnancy & < 12 months postpartum | Grade 0 I II III | 35(24–48) | 18 | OS | paper | 0.59 | 0.29–1.17 | 7 | Age, year of diagnosis | Tumour grade, ER status, LN involvement |
Azim, 2012-OS [52] | Italy | 65 | 130 | Pregnancy | NA | < 50 | 6 | OS | paper | 1.70 | 0.80–3.90 | 7 | Age, year of surgery, pathological tumour size, pathological nodal status | pN, neoadjuvant chemotherapy, ER |
Azim, 2012-DFS [52] | Italy | 65 | 130 | Pregnancy | NA | < 50 | 6 | DFS | paper | 2.30 | 1.30–4.20 | 7 | Age, pT, pN, neoadjuvant chemotherapy, Ki-67, HER2, perivascular invasion | |
Ali, 2012-OS [53] | USA | 40 | 40 | Pregnancy & < 12 months postpartum | Stage I II III IV | 33(24–42) | 16 | OS | indirect | 2.15 | 1.13–4.09 | 7 | – | Age and stage-matched |
Ali, 2012-DFS [53] | USA | 40 | 40 | Stage I II III IV | 33(24–42) | 16 | DFS | indirect | 2.00 | 1.12–3.59 | 7 | – | ||
Amant, 2013-OS [54] | Belgium | 311 | 865 | Pregnancy | Stage I II III, Grade I II III | 33(31–36) | 5 | OS | paper | 1.19 | 0.73–1.93 | 8 | – | Age at diagnosis, stage, grading, histologic tumour type, ER/PR status, HER2, chemotherapy |
Amant, 2013-DFS [54] | Belgium | 311 | 865 | Pregnancy | Stage I II III, Grade I II III | 33(31–36) | 5 | DFS | paper | 1.34 | 0.93–1.91 | 8 | – | |
Litton, 2013-OS [55] | USA | 75 | 150 | Pregnancy | Stage I II III | 24–45 | 5 | OS | paper | 1.87 | 1.04–3.36 | 7 | Age at diagnosis, stage at diagnosis, year of diagnosis | Age at diagnosis, year of diagnosis, clinical cancer stage, tumour nuclear grade |
Litton, 2013-DFS [55] | USA | 75 | 150 | Pregnancy | Stage I II III | 24–45 | 5 | DFS | paper | 2.09 | 1.19–3.67 | 7 | ||
Valentini, 2013 [56] | USA | 75 | 269 | Pregnancy & < 12 months postpartum | NA | 32.5(20–45) | 15 | OS | paper | 0.79 | 0.25–2.44 | 7 | – | Age at diagnosis, tumour size, lymph node status, ER status, use of chemotherapy, oophorectomy |
Dimitrakakis, 2013 [57] | Greece | 39 | 39 | Pregnancy & < 12 months postpartum | Stage I II III IV, Grade I II III | 34.3 ± 5.0 | 5 | OS | paper | 9.28 | 2.94–29.27 | 6 | Stage, age, year of diagnosis | Stage, ER status, grade, age at diagnosis |
Calliha, 2013-OS [58] | USA | 76 | 86 | Pregnancy & < 60 months postpartum | Stage 0 I II III IV, Grade I II III | ≤45 | 5 | OS | paper | 2.65 | 1.09–6.42 | 6 | – | Tumour biological subtype, clinical stage, year of diagnosis |
Calliha, 2013-DFS [58] | USA | 74 | 84 | Pregnancy & < 60 months postpartum | Stage 0 I II III IV, Grade I II III | ≤45 | 5 | DFS | paper | 2.80 | 1.12–6.57 | 6 | – | Tumour biological subtype, clinical stage, year of diagnosis, local recurrence |
Bell, 2013-OS [59] | Australia | 13 | 377 | Pregnancy & < 12 months postpartum | NA | < 48 | 5 | OS | paper | 2.50 | 0.5–11.7 | 6 | – | – |
Bell, 2013-DFS [59] | Australia | 13 | 377 | Pregnancy & < 12 months postpartum | NA | < 48 | 5 | DFS | paper | 0.90 | 0.2–4.4 | 6 | – | – |
Moller, 2013 [60] | UK | – | – | – | Stage I II III IV | 10–54 | 10 | OS | paper | – | – | 7 | – | Age, stage |
Framarino-dei-Malatesta, 2014 [61] | Italy | 22 | 45 | Pregnancy | NA | 37.2 ± 3.2 | 10 | OS | indirect | 0.96 | 0.29–3.21 | 6 | Age | – |
Madaras, 2014 [62] | Hungary | 31 | 31 | Pregnancy & < 12 months postpartum | – | 34 | 10 | OS | indirect | 5.76 | 2.09–15.98 | 7 | Age, year of first breast cancer diagnosis | – |
Nagatsuma, 2014 [63] | Japan | – | – | – | Stage 0 I II III IV, Grade I II III | 26–44 | 10 | OS | paper | – | – | 7 | – | Age at diagnosis, AJCC clinical stage, histological tumour grade, oestrogen and progesterone receptor status, HER2 status |
Strasser-Weippl, 2014 [64] | China | 109 | 1274 | Pregnancy & < 60 months postpartum | Grade I II III | < 45 | 5 | DFS | paper | 1.62 | 1.04–2.54 | 8 | – | Age, oestrogen receptor, progesterone receptor, HER2 status, disease stage |
Genin, 2015-OS [65] | France | 87 | 174 | Pregnancy & < 12 months postpartum | Grade I II III | 35(27–40) | 10 | OS | indirect | 1.09 | 0.79–1.52 | 7 | Age, year of diagnosis | – |
Genin, 2015-DFS [65] | France | 87 | 174 | Pregnancy & < 12 months postpartum | Grade I II III | 35(27–40) | 10 | DFS | paper | 1.87 | 1.05–3.33 | 7 | Age, year of diagnosis | Age, ER, HR status, tumour stage, HER2 status, Ki-67 rate |
Iqbal, 2017 [14] | Canada | 501 | 5832 | Pregnancy & < 21 months postpartum | Stage I II III IV | 20–45 | 5 | OS | paper | 1.11 | 0.86–1.45 | 9 | – | Year of diagnosis, age, tumour size, nodal status, oestrogen receptor status, progesterone receptor status, chemotherapy, radiotherapy, et al |
Kim, 2017 [66] | Korea | 344 | 668 | Pregnancy & < 12 months postpartum | Stage 0 I II III IV, Grade I II III | 20–45 | 10 | OS | indirect | 1.85 | 1.28–2.67 | 8 | Operation period, age, initial stage | – |
Bae, 2018(1) [67] | Korea | 40 | 2770 | Pregnancy & < 12 months postpartum | Stage 0 I II III | 33.5 (27–40) | 5 | CSS | paper | 4.00 | 1.20–12.90 | 8 | – | Age, stage, chemotherapy |
Bae, 2018(2) [68] | Korea | 411 | 83,381 | Pregnancy & < 12 months postpartum | Stage 0 I II III IV | 20–49 | 15 | OS | paper | 1.03 | 0.74–1.42 | 9 | – | Age at diagnosis, stage, high versus low/intermediate, luminal subtype, HER2 subtype, et al |
Boudy, 2018-DFS [16] | France | 49 | 51 | Pregnancy | Grade I II III | < 46 | 5 | DFS | indirect | 1.19 | 0.75–1.91 | 8 | Propensity score | – |
Boudy, 2018-CSS [16] | France | 49 | 51 | Pregnancy | Grade I II III | < 46 | 5 | CSS | indirect | 1.06 | 0.65–1.72 | 8 | – | |
Johansson, 2018 [2] | Sweden | 778 | 1661 | Pregnancy & < 24 months postpartum | Stage 0 I II III IV | 15–44 | 10 | OS | indirect | 0.90 | 0.55–1.40 | 9 | – | Age, period, education, region, tumour characteristics, pathologic T stage, N stage, ER/PR |
Chuang, 2018 [69] | China (Taiwan) | – | – | – | Stage I II III | 20–50 | > 10 | OS | paper | – | – | 9 | – | Age and year of diagnosis, stage, tumour size, positive lymph nodes, histological grading, treatments |
Ploquin, 2018-OS [15] | France | 111 | 253 | Pregnancy | Stage 0 I II III IV | 22–46 | 5 | OS | paper | 1.10 | 0.67–1.79 | 8 | Age, clinical T stage, hormone receptor | Clinical nodal status, age |
Ploquin, 2018-DFS [15] | France | 111 | 253 | Pregnancy | Stage 0 I II III IV | 22–46 | 5 | DFS | paper | 1.15 | 0.78–1.68 | 8 | ||
Suleman, 2019-OS [70] | Saudi Arabia | 110 | 114 | Pregnancy | Stage I II III IV | 20–48 | > 10 | OS | indirect | 2.58 | 1.26–5.26 | 7 | Diagnosed year | – |
Suleman, 2019-DFS [70] | Saudi Arabia | 110 | 114 | Pregnancy | Stage I II III IV | 20–48 | > 10 | DFS | indirect | 1.18 | 0.70–1.97 | 7 | – | |
Choi, 2019 [17] | Korea | 63 | 3804 | Pregnancy & < 12 months postpartum | NA | < 50 | 10 | OS | paper | 1.52 | 0.82–2.83 | 8 | – | Histologic type, stage, ER, PR, age at diagnosis, Charlson comorbidity index |