Can the risk of secondary cancer induction after breast conserving therapy be reduced using intraoperative radiotherapy (IORT) with low-energy x-rays?

Table 3 Lifetime risk of secondary cancers for organs doses from different breast radiotherapy techniques.

Organs	Probability (%/Sv)	IORT	APBI	EBRT
Contralateral Breast	0.20	(< 0.06%*)	(< 0.11%*)	0.22% (< 2.08%*)
Ipsilateral lung	0.85	0.02%	0.11%	2.9%
Contralateral lung	0.85	(< 0.25%*)	(< 0.47%*)	0.2% (< 0.85%*)

The probability per Sievert was taken from the National Council on Radiation Protection and Measurements (NCRP) Report 116. Mean organ doses were used for the calculation of secondary cancer risk (*maximal doses were used where mean doses were not available). Note that RBE effects were not taken into account, which may be up to a factor of 1.3 - 3 for IORT (see discussion).