Future Potential Clinical Applications of Spectroscopic Techniques in Human Diseases - Vibrational Spectroscopy for Tissue Analysis - page 298

do not always accurately reflect the presence or absence of tumour metastases.
In addition, CT cannot reliably distinguish between benign and malignant
lung nodules, hence the need for biopsy and histological confirmation [17].
Positron emission tomography (PET)-CT scanning appears to be valuable
in deciding whether a nodule is benign or malignant, as well as in staging
loco-regional and distant metastatic disease. However, it cannot distinguish
between inflammatory conditions and malignancy, and is of limited value in
lesions smaller than one centimetre [18,19].
Biopsy, of course, provides the precise type of lung cancer, but it is pos-
sible to have a negative biopsy due to sampling error, necessitating the need
for repeat biopsy. It is not always easy to repeat procedures for obtaining
a biopsy, as the procedures that allow biopsy, including bronchoscopy and
mediastinoscopy, are not without significant risks.
It should be possible in the future to diagnose lung cancer with spectros-
copy and to distinguish between various subtypes of lung cancer, as well
as reliably detect cancer in mediastinal lymph nodes, with the development
of a probe for use with spectroscopy. It should be possible to use the probe
while obtaining a biopsy because if the first biopsy happens to miss tissue,
a second biopsy could be avoided, due to live confirmation of diagnosis via
probe at the time of the first biopsy. In addition, it should be possible to dif-
ferentiate between benign and malignant lung nodules, and to determine
the origin of metastases in the lung from various primary cancers.
In addition, as discussed in Chapter 5 in great detail, spectroscopy
could potentially be employed in many other cancer diagnostics, includ-
ing head and neck carcinomas, skin cancers, pancreatic cancers, gastric and
oesophageal cancers, hepatocellular carcinomas, and others.
Determination of Prognostic Factors
Amongst prognostic factors, tumour grade is an excellent indicator of bio-
logical potential. However, reliable assessment of tumour grades has been
hindered in the past by difficulties in determining reproducible criteria and
the problem of interobserver variability [20,21].
In recent years, it has been learned that breast cancer is not a single entity,
but rather a heterogeneous disease comprised of distinct biological subtypes
with diverse natural history, and presents a varied spectrum of clinical,
pathologic, and molecular features with different prognostic and therapeutic
implications. The four breast cancer subtypes are currently defined by immu-
nohistochemistry (IHC) expression of oestrogen receptor (ER) or progester-
one receptor (PR) and human epidermal growth factor receptor 2 (HER2) and
include: ER/PR + , HER2 + ; ER/PR + , HER2 - , ER/PR - , HER2 + , and ER/PR, HER2 - .
The ER/PR - , HER2 - (also called triple negative ) subtype of breast cancer is