Table 6.

Top 16 largest clusters of co-cited references.

Cluster ID	Size	Silhouette	Mean (year)	Top terms (log-likelihood ration, p-level)
0	282	0.872	2000	metastatic breast cancer (33893, 1.0E-4); phase ii study (26053.84, 1.0E-4); first-line chemotherapy (25660.09, 1.0E-4); weekly docetaxel (20912.61, 1.0E-4); her2-positive metastatic breast cancer (17395.53, 1.0E-4)
1	223	0.852	2011	her2-positive metastatic breast cancer (82757.77, 1.0E-4); trastuzumab emtansine (78550.48, 1.0E-4); her2-positive breast cancer (21337.09, 1.0E-4); human epidermal growth factor receptor (19711.43, 1.0E-4); 2-positive metastatic breast cancer (17307.24, 1.0E-4)
2	178	0.922	2000	her2 testing (8047.09, 1.0E-4); trastuzumab therapy (5688.99, 1.0E-4); her2-overexpressing metastatic breast cancer (5498.52, 1.0E-4); trastuzumab-based treatment (5382.05, 1.0E-4); trastuzumab emtansine (5040.84, 1.0E-4)
3	177	0.957	2008	circulating tumor cell (132909.22, 1.0E-4); circulating tumour cell (11263.83, 1.0E-4); molecular characterization (8257.72, 1.0E-4); peripheral blood (6694.55, 1.0E-4); small-cell lung cancer (5965.34, 1.0E-4)
4	176	0.895	2011	endocrine therapy (42273.75, 1.0E-4); hormone receptor-positive (27059.57, 1.0E-4); cyclin-dependent kinase (21029.84, 1.0E-4); postmenopausal women (19147.25, 1.0E-4); aromatase inhibitor (18871.73, 1.0E-4)
5	108	0.907	2015	cell-free dna (17995.34, 1.0E-4); circulating tumor dna (7739.3, 1.0E-4); circulating cell-free dna (4809.94, 1.0E-4); circulating tumour dna (4683.08, 1.0E-4); estrogen receptor (4315.13, 1.0E-4)
6	107	0.918	2005	brain metastases (18889.44, 1.0E-4); metastatic breast cancer cell (16602.25, 1.0E-4); breast cancer metastasis (14853.17, 1.0E-4); breast cancer cell (8942.98, 1.0E-4); metastatic triple negative breast cancer (8619.06, 1.0E-4)
7	91	0.956	2006	first-line bevacizumab (9329.12, 1.0E-4); antiangiogenic therapy (5458.64, 1.0E-4); metronomic chemotherapy (4612.44, 1.0E-4); her2-negative metastatic breast cancer (3509.24, 1.0E-4); athena study (2973.34, 1.0E-4)
8	81	0.941	2011	stage iv breast cancer (16893.88, 1.0E-4); de novo (8648.98, 1.0E-4); recurrent metastatic breast cancer (8360.75, 1.0E-4); population-based study (7316.55, 1.0E-4); locoregional therapy (5554.6, 1.0E-4)
9	44	0.984	2004	new therapeutic option (860.62, 1.0E-4); epothilone b analog ixabepilone (810.67, 1.0E-4); incorporating recent data (635.8, 1.0E-4); clinical perspective (635.8, 1.0E-4); integrating epothilone (635.8, 1.0E-4)
10	43	0.946	2011	eribulin mesylate (21074.96, 1.0E-4); absolute lymphocyte count (6191.24, 1.0E-4); eribulin monotherapy (5156.28, 1.0E-4); eribulin mesilate (5123.9, 1.0E-4); phase ii multicenter (4727.03, 1.0E-4)
11	30	0.96	2016	parp inhibitor (2020.08, 1.0E-4); mutational burden (1747.73, 1.0E-4); asco guideline (1452.97, 1.0E-4); 2 mutation (1433.36, 1.0E-4); high tumor (1328.53, 1.0E-4)
12	29	0.958	2009	receptor conversion (2340.94, 1.0E-4); biomarker discordance (1535.19, 1.0E-4); receptor status (1183.91, 1.0E-4); metastatic relapse (855.84, 1.0E-4); different distant breast cancer metastases (845.45, 1.0E-4)
13	23	0.999	1995	psychosocial intervention (2301.59, 1.0E-4); supportive-expressive group therapy (1976.67, 1.0E-4); cancer patient (1664.48, 1.0E-4); psychosocial support (1180.24, 1.0E-4); psychological intervention (1144.13, 1.0E-4)
14	18	0.997	1994	high-dose chemotherapy (2084.12, 1.0E-4); autologous stem cell transplantation (851.22, 1.0E-4); undergoing high-dose chemotherapy (851.22, 1.0E-4); autologous hematopoietic stem cell transplantation (459.06, 1.0E-4); patient selection (459.06, 1.0E-4)
15	11	0.994	1991	methotrexate-mitomycin c (150.03, 1.0E-4); randomized controlled (150.03, 1.0E-4); cooperative group (117.25, 1.0E-4); metastatic breast carcinoma (109.07, 1.0E-4); first-line single-agent mitoxantrone (78.01, 1.0E-4)