Radiation risks associated with serial imaging in colorectal cancer patients: Should we worry?

Table 1 Summary of follow up recommendations including imaging for patients with colorectal cancer

Ref.	History and physical	CEA	Abdominal imaging	Pelvic CT	Chest imaging	Colonoscopy	Sigmoidoscopy
NCCN 2010[3]	Q3-6m for 2 yr then Q6m for 3 yr	Q3-6m for 2 yr then Q6m for 3 yr	CT annual 3-5 yr	Annually 3-5 yr for rectal cancer patients	CT annually 3-5 yr	1 yr then as clinically indicated
PEBC 2010[4] Stage IIb-III	Q6m for 3 yr then annual for 2 yr	Q6m for 3 yr then annual for 2 yr	US Q6m for 3 yr then annual for 2 yr		CXR Q6m for 3 yr then annual for 5 yr	Yearly as long as polyps are found. If no polyps repeat 3-5 yr
ESMO 2010[5]	Colon Q3-6m for 3 yr then Q6-12m for 2 yrRectal Q6m for 2 yr		Colon CT or contrast enhanced US Q6-12m for 3 yrRectal CT 1 and 3 yr		Colon CT Q6-12m for 3 yrRectal CT 1 and 3 yr after surgery	Colon Q1 yr then Q3-5 yrRectal Q5 yr	Rectal Q3-6m for 1 yr then Q6-12m
BSG/ACGBI 2010[6]			CT within 2 yr			5 yr after surgery then 5 yr intervals
ACS 2006[7] Stage II or III						12m, then at 3 yr and 5 yr
ASCO 2005[8] Stage II or III	Q3-6m for 3 yr then at physicians discretion	Q3m for at least 3 yr	CT annual for 3 yr	Consider for rectal cancer patients	CT annual for 3 yrCXR not recommended	At 3 yr, if normal then Q5 yr	Q6m for rectal cancer patients who have not received pelvic radiation
Australia NHMRC 2005[9]	Q3-6m for 2 yr then Q6-12m thereafter	Q3-6m with clinical review	CT recommended No schedule	CT recommended No schedule	CT recommendedNo schedule	Q3-5 yr initially then Q3-5 yr	Rectal Q3-6m then Q6-12m
ASCRS/SPTF 2004[10]	Q4m for 2 yr	Q4m for 2 yr	Not recommended		CXR: insufficient evidence	3 yr after surgery then Q3 yr
NZGG 2011[11]	Q6m for 2 yr then yearly to 5 yr					3-5 yr after surgery then Q3-5 yr	Rectal Q6m for 2 yr then yearly to 5 yr

CEA: Carcinoembryonic antigen; CT: Computed tomography.

Table 2 Characteristics of studies included for qualitative analysis

Ref.	Study year	Country	Study size	Intervention	Study type
BEIR VII report[15]	2006	United States	Comprehensive review of all relevant biological, physical and epidemiological radiation data
Pearce et al[21]	2012	United Kingdom	178604 for leukaemia and 176587 for brain tumour analysis respectively	CT scan	Retrospective
Woo et al[22]	2012	Canada	1424	Pulmonary CT angiography	Retrospective
Meer et al[23]	2012	United States	Two 4-yr cohorts of 5267230 and 5555345	CT scan	Retrospective
Muchow et al[24]	2012	United States	617	Cervical spine multidirectional CT	Retrospective
Huda et al[25]	2012	United States	CT scan simulation
Perisinakis et al[26]	2012	Greece	Triple-rule-out 256-slice CT angiography simulation
Zondervan et al[27]	2012	United States	25104	Chest and abdomino-pelvic CT scan	Retrospective
van Walraven et al[28]	2011	Canada	2569	Abdomino-pelvic CT scan	Retrospective
Kuhns et al[29]	2011	United States	CT scan simulation
Davis et al[30]	2011	United States	205 cases, 333 controls	Survey asking ionizing radiation exposure	Case-control
Berrington de González et al[31]	2011	United States	CT colonography simulation
Li et al[32]	2011	United States	CT scan simulation
Huda et al[33]	2011	United States	Cardiac CT angiography simulation
Adams et al[34]	2010	United States	7490	Chest radiotherapy	Prospective cohort
Noor et al[35]	2011	United Kingdom	202	Plain X-ray, CT scan, nuclear medicine procedures, cardiac procedures	Retrospective
Perisinakis et al[19]	2010	Greece	Coronary CT angiography simulation
Faletra et al[36]	2010	Switzerland	729	64-slice coronary CT angiography	Prospective
Feng et al[37]	2010	China	CT scan simulation
Richards et al[38]	2010	United Kingdom	Spine CT simulation
Kim et al[39]	2010	United States	Cone beam CT simulation in a paediatric population
Smith-Bindman et al[40]	2009	United States	1119	CT scan	Retrospective
Berrington de González et al[41]	2009	United States	57 million CT scans	CT scan	Retrospective
Raelson et al[42]	2009	United States	68	Neuroangiography	Retrospective
Kim et al[43]	2009	United States	Multi-detector CT scan simulation
King et al[44]	2009	United States	Two cohorts of 240 participants respectively	CT scan	Retrospective
Sodickson et al[45]	2009	United States	31462	CT scan	Retrospective
Griffey et al[46]	2009	United States	130	CT scan	Retrospective
Huang et al[47]	2009	Hong Kong	Fluorine 18-fluorodeoxyglucose PET/CT scan simulation
Einstein et al[48]	2008	United States	16-slice CT coronary angiography simulation
Chodick et al[49]	2007	Israel	17686 CT scans	CT scan	Retrospective
Beyan et al[50]	2007	Turkey	15	Radiologic imaging studies in diagnosis and follow-up of Hodgkin’s lymphoma	Retrospective
Berrington de González et al[51]	2007	United States	CT scan simulation
Blettner et al[52]	2007	Germany	Glioma and meningioma-747 cases, 1535 controls. Acoustic neuroma-97 cases, 202 controlsInterviews collecting data on diagnostic X-ray examinations, radiotherapy, CT scans, scintigrams and angiographiesCase-control
Einstein et al[53]	2007	United States	64-slice CT coronary angiography simulation
de Jong et al[54]	2006	Netherlands	CT scan simulation
Brenner et al[55]	2004	United States	CT scan simulation
Berrington de González et al[56]	2004	United Kingdom	Frequency of X-ray exposure estimated using worldwide survey of medical radiation use between 1991-1996	Diagnostic X-rays	Retrospective

CT: Computed tomography.