Raman Spectroscopy for Early Cancer Detection, Diagnosis and Elucidation of Disease-Specific Biochemical Changes - Emerging Raman Applications and Techniques in Biomedical and Pharmaceutical Fields - page 316

(5-15%) and the poor outcome in patients who present with invasive adeno-
carcinoma of the oesophagus (30% survival at 1 year and 8% survival at 5 years
for men in England and Wales diagnosed in 2000-2001) [82]. Currently there is
a dramatic rise in the incidence of adenocarcinoma centred on the UK [83, 84].
In 2005 in the UK 2% of all cancers diagnosed were oesophageal (7,823) but
(in 2006) 5% of all cancer deaths were from oesophageal cancer (7,405) [85].

13.2.1 The Current Gold Standard

Patients with pre-malignant conditions are routinely identified through en-
doscopic surveillance programmes, during which blind biopsies are taken and
examined at a cellular level by a histopathologist; the 'gold standard' for the
diagnosis and detection of malignancies and pre-malignancies. Histopathology
relies upon sectioning tissue to less than one cell thick ( < 10

m) and staining
with haematoxylin and eosin (H&E). This provides some general functional
information in addition to the morphologic arrangement of the tissue that
can be viewed under a conventional light microscope. The principle of his-
tology has changed little since its conception in the 19th century [86]. One
problem associated with the gold standard involves the targeting of biopsy
samples from microscopic abnormal lesions. Generally a random tissue selec-
tion procedure must be employed in the detection of early lesions, which can
lead to a high probability of missing abnormal tissue [87]. Biopsy also has in-
herent risks, including perforation and bleeding. In vivo optical biopsy using
Raman spectroscopy has many clinical benefits, including obviating the need
for the excisional tissue biopsy, reducing trauma to the patient and the clini-
cians' workload, especially that of the pathologist. Further, an in vivo Raman
biopsy could eliminate the need for many secondary procedures, by enabling
treatment to take place directly following diagnosis or by ensuring resection
margins are accurately defined. This is likely to improve patient outcomes and
decrease waiting times by reducing the number of costly procedures required.

μ

13.2.2 Development of Oesophageal Raman Spectroscopy

A myriad of studies have been undertaken to explore the use of Raman spec-
troscopy to discriminate diseased from healthy tissues. The early studies gen-
erally involved only normal and cancerous tissues, but as researchers have
improved their understanding of the clinical processes involved they have re-
alised the need to include as many pathology groups as are likely to be found
in the organ of interest. The carcinogenesis process in epithelial tissues follows
a complex biochemical pathway and Raman spectroscopy is able to measure
aspects of these molecular changes, but they are often very subtle and may
require good signal to noise spectra and multivariate analysis techniques for
reliable discrimination.