Table 2.

Moderate hypofractionation—invasive breast cancer.

Trial	Sample Size	Inclusion Criteria	RT Technique	Fractionation	Boost	Outcomes	Median Follow-Up	Results
OCOG [42,44]	1234	pT1-2 post lumpectomy	2D (including cobalt) and 3D	42.5 Gy in 16 fx 50 Gy in 25 fx	No	LRIC; DR, BC, LRT.	5.9 years	5 yr LRIC: 97.2% (Short Arm), 96.8% (Long Arm), Abs Difference: 0.4% (95% CI: −1.5% to 2.4%) 3 yr BC: 76.8% (Short Arm), 77.0% (Long Arm), Abs Difference: −0.6% (95% CI: −6.5% to 5.5%)
START A [41] and B [43]	START-A 2236 START-B 2215	pT1-3a pN0-1 M0) requiring radiotherapy after primary BCS or mastectomy, with clear tumor margins ≥1 mm	2D (including cobalt) and 3D	START-A: f 50 Gy in 25 fx over 5 weeks with 41.6 Gy or 39 Gy in 13 fx START-B: 50 Gy in 25 fx with 40 Gy in 15 fx	Yes in 42.6% with 10Gy	LR and LRT	9.3 years for START-A, and 9.9 years for START-B.	START-A: 10 yr LR: 6.3% (41.6 Gy), 7.4% (50 Gy, HR 0.91, p = 0.65), 8.8% (39 Gy, HR 1.18, p = 0.41) START-B: 10 yr LR: 4.3% (40 Gy), 5.5% (50 Gy, HR 0.77, p = 0.21)
DBCG HYPO [52]	1854	>40 years of age after BCS for node-negative breast cancer or DCIS (13%)	3D	50 Gy in 25 fx 40 Gy in 15 fx	Yes, 23.1% received 10 Gy as boost	BI and LR	7.26 years	3 yr BI: 11.8% (50 Gy), 9.0% (40 Gy), risk difference: −2.7% (p = 0.07) 9 yr LRR: 3.3% (50 Gy), 3.0% (40 Gy) 9 yr OS: 93.4% (both 50 Gy and 40 Gy)
Peking Union Medical College, Beijing, China [46]	820	Post-mastectomy pT3-4 N+ (at least 4 nodes)	2D	50 Gy in 25 fx 43.5 Gy in 15 fx Including chest wall and nodal irradiation	No	5-year LRR	5 years	5-year LRR: 8.3% (hypofractionated) vs. 8.1% (conventional), HR 1.10, 90% CI 0.72 to 1.69, p < 0.0001

Legend: LRIC: local recurrence of invasive cancer; LRR: locoregional recurrence; DFS: disease-free survival; DR: distant recurrence; BC: breast cosmesis; LRT: late radiation toxicity; BI: breast induration; LR: local-regional tumour relapse; OS: overall survival; BCS: breast cancer-specific survival; BCS: BCS surgery; fx: fractions.