Is it useful to combine sputum cytology and low-dose spiral computed tomography for early detection of lung cancer in formerly asbestos-exposed power industry workers?

Table 2 Cases of lung cancer among 187 high risk participants with CT scan and sputum examination

No.	Examination^a	Location^b	Diagnosis^c	Histology^d	Stage	Survival^e
1	b	per	CT + spu	SQC	IIIa
2	r	per	CT + spu	SQC	Ia	29
3	b	per	CT	ADO	Ia
4^g	b	per	CT			7
5	r	per	CT	LAC	IIIb	23
6	b	per	CT	ADO	Ia	64
7	b	cen	CT + spu	SQC	IV	21
8	b	cen	CT + spu	SQC	Ia
9	r	cen	CT + spu	SQC	IIb	33
10	b	cen	CT + spu	SQC	Ib	18
11	b	cen	CT	SMC	Ia	28
12	r	cen	spu	SQC	IIIb	72
13	i	cen		SMC	IIb	14
14	i					35
15^h	f
16	f			SMC	IIIb	^k
17	f			SMC	IIb	^k
18	f				IIIb	^k

^aExamination with significant result: b = baseline, r = re-examination, i = interval, f = follow-up.
^bLocation of tumour: per = peripheral, cen = central.
^cResult indicating diagnosis: CT = low-dose spiral computed tomography, spu = sputum cytology.
^dHistology of lung carcinoma: SQC = squamous cell, ADO = adeno, LAC = large cell, SMC = small cell.
^eSurvival time after beginning of initial clinical symptoms indicating the disease (months).
^gDied suddenly 2004 before biopsy could be taken, diagnosis unequivocal clinically and on CT.
^hDied 2008 with lung cancer after refusing further examinations.
^kAlive by the end of follow-up.
In patients with missing data the documented histories were incomplete or could not be retrieved in time.