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6.0) BRIEF RESUME OF THE INTENDED WORK:
6.1) NEED FOR STUDY:
Incidence of breast cancer is on the rise in developing countries like India.
External beam radiotherapy is being standardly used to treat breast malignancy. With the
advent of newer radiotherapy techniques and targeted therapy to treat breast cancer
survival rates has tremendously increased.
About two to eleven percentage of women diagnosed with breast cancer will
develop contralateral breast cancer in their life time¹. Breast is a highly sensitive structure
for radiation induced carcinogenesis. The possibility of increasing the carcinogenesis risk
from the dose delivered to the contralateral side is of particular concern to patients as
well as Radiation Oncologists. Thus the need of this study is to quantify the radiation
dose received by the contralateral breast during treatment of breast cancer by various
radiotherapy techniques.
6.2) REVIEW OF LITERATURE:
With advent of newer radiotherapy techniques and early screening to address
breast cancer, nowadays survival rates are described in terms of 10 years survival rather
than 3 years survival 30 years back.with such improval in survival rates,it is essential to
analyse any factors which may contribute to therapy related increased risk of developing
second malignancies in the long term.
About 2-11% of women diagnosed with Breast Cancer will develop contralateral
breast cancer in their life time¹.A population based Cohort study done at Denmark
involving 56,237 subjects suggested a link of prior radiotherapy and contralateral Breast
Cancer2. Murakami et al observed an excess risk of contralateral breast cancer in the
Radiotherapy group (SIR, 7.6) compared with the Non radiotherapy group (SIR, 2.9)3.
.Incidence of radiation induced breast cancer is a linear function of dose received by the
contralateral Breast and the latent period is over 10 Years4.
During a course of radiotherapy, patients will receive some out of field dose,
which is mainly attributed to internal and external scatter, as well as collimator leakage5.
There are several methods of measuring this dose to the contralateral breast while patient
is undergoing radiotherapy namely MOSFIT device,CaSo4 TLD and Lithium fluoride
TLD discs or chips.When measured with ThermoLuminescenceDosemeter (TLD) discs,
the contralateral breast was found to receive 3.05 – 6.05% of total dose to diseased side6.
Also, there is evidence in the literature of various studies measuring and
comparing the dose to contralateral breast by various radiotherapy techniques.By
comparing ½ beam block with Isocentric technique, it was suggested that a significant
reduction in contralateral breast dose can be accomplished by adoption of Isocentric
techniques7.A study done at All India Institute of Medical Sciences showed that the
highest contralateral breast doses were contributed by medial wedged fields.The average
skin dose measured at the nipple was 2.1-10.9% of the isocentre dose. The dose to the
contralateral breast can be reduced by using IMRT or avoiding wedging the medial
tangential fields8.In a comparison of four primary breast irradiation techniques, dose to
contralateral breast increases with the use of medial wedge and cerrobend half beam
block gives highest opposite breast dose. The lowest contralateral dose is with the
asymmetric jaw with no medial wedge and no blocks9.
Hence we undertake a study to measure the dose received by contralateral breast
during various breast irradiation techniques.
6.3) OBJECTIVES OF STUDY:

To Quantify the amount of radiation dose received by contralateral breast while
treating cancer of the other breast by various Radiotherapy techniques.

To Compare and analyse the influence of various techniques on the dose received
by the contralateral breast.
7.0) MATERIALS AND METHODS:
7.1) SOURCE OF DATA:
The study is being conducted on all histopathologically proven cases of breast
cancer attending the Department of Radiation Oncology at M.S Ramaiah Medical
College Hospital.
7.2) METHODS OF COLLECTION OF DATA:
Sample Size:
The estimation of sample size is in consultation with a biostatistician. The sample
size is to be taken is 44.
7.3) Inclusion Criteria:

All female Breast Cancer patients who had undergone conservative Breast
Surgery or Mastectomy.
7.4) Exclusion Criteria:

Patients with any form of prior radiotherapy to the breast.

Patients with histopathologically proven bilateral breast cancer.
Informed consent will be taken from all patients included in the study. Precalibrated and
standardized Lithium Fluoride Thermo Luminescence Dosemetry (TLD) chips (3×3×0.9mm) will
be placed on the skin surface of contralateral breast, one at the level of nipple (P1) and another
TLD at 5cm lateral from the edge of the medial tangential field (P2). Three sets of measurements
(At 1st week, 3rd week and 5th week) will be taken and the readings will be done on a HarshawQS3500 TLD reader and averaged.
The dose received by the contralateral breast is measured as a percentage of the
dose prescribed at the reference point on the affected side.
Finally the influence of various techniques namely use of wedges (SAD), use of
Breast cone (SSD),Influence of Gantry angle, Half beam Block and type of radiation used
will be analysed.
The duration of the study is from November 2007 to July 2009.
Statistical Analysis will be done by Descriptive method of
stastistical
analysis.
7.5) Does the study require any investigation or interventions to be conducted on
patients or other humans or animals? If so, please describe briefly. No.
7.6) Has ethical clearance been obtained from your institution in case of 7.6-Yes.
8.0) LIST OF REFERENCES
1) Yue Chen,Wendy Thompson et al,Epidemiology of contralateral Breast
cancer,Cancer Epidemiology,Biomarkers and Prevention,1999;vol.8:855-61.
2) Storm HH, Jenson OM; Risk of Contralateral Breast Cancer in Denmark 1943-1980,
Br.J Cancer 1986;54:483-492.
3) Marakami R,Hiyama T et al,Second primary Cancers following female breast cancer
in Osaka,Japan: Jpn. J. clin.oncol.,1987;17:293-302.
4) Muller-Rankel R,Kalokhe UP.Scatter Dose from Tangential Breast Irradiation to the
involved Breast. Radiology 1994; 191:853-855.
5) Frass, B.A;Robertson, P.L;Dose to the Contralateral Breast due to Primary Breast
Irradiation, IJROBP 1983 ;10: 809-818.
6) Chougule A. Radiation dose to contra lateral breast during treatment of breast
malignancy by radiotherapy. J Can Res Ther 2007;3:8-11.
7) Tercilla et al, Comparison of Contralateral Breast Doses from ½ beam block and
Isocentric treatment for Breast Irradiation, IJROBP,1989; Vol.17: P.205-210.
8) Prabhakar R, Rath GK, A study of Contralateral Breast Surface dose for various
tangential field techniques, Aus Phys. Eng. Sci Med. 2007.Mar; 30(1) 42-5 links.
9) Charmayne A.Kelly MD et al, Dose to Contralateral Breast: A Comparison of Four
Primary Breast Irradiation techniques, IJROBP 1996;34(3), p.727-732,.