Table 2.

Distribution of histologic grades in different invasive breast cancer studies

Study	Number	Grade 1	Grade 2	Grade 3
Elston, 1984 [45]	625	17%	37%	46%
Davis et al., 1986 [46]	1537	22%	49%	29%
Hopton et al., 1989 [47]	874	29%	46%	25%
Le Doussal, et al., 1989 [35]	1262	11%	45%	46%
Balslev et al., 1994 [48]	9149	32%	49%	19%
Saimura et al., 1999 [22]	741	19%	37%	44%
Reed et al., 2000 [30]	613	25%	41%	35%
Simpson et al., 2000 [24]	368	22%	45%	33%
Lundin et al., 2001 [23]	1554	26%	47%	27%
Frkovic-Grazio and Bracko, 2002 [16]	270	38%	38%	24%
Warwick et al., 2004 [26]	1988	23%	37%	40%
Williams et al., 2006 [49]	1058	20%	46%	34%
Rakha et al., 2008 [7]	2219	18%	36%	46%
Thomas et al., 2009 [50]	1650	26%	45%	29%
Blamey et al., 2010 [27]	16,944	29%	41%	30%
Puig-Vives et al., 2013 [51]	2122	20%	47%	33%
Seneviratne et al., 2015 [52]	2146	25%	52%	23%
Sun et al., 2015 [53]	1259	18%	62%	20%
Moller et al., 2016 [54]	81,427	16%	52%	32%
Van Dooijeweert et al., 2019 [55]	33,792	28%	48%	24%
Van Dooijeweert et al., 2020 [56]	17,102	31%	49%	19%