Page 231 - Concise Pathology for Exam Preparation ( PDFDrive )

216 SECTION I General Pathology

TABLE 9.2. Effects of whole body irradiation
0–1 Sv 1–2 Sv 2–10 Sv 10–20 Sv .50 Sv
Major site of injury – Lymphocytes Bone marrow Small bowel CNS
Clinical presenta- – Neutropenia and Leukopenia, haem- Nausea, vomiting, di- Nausea, vomiting,
tion lymphopenia orrhage, alopecia arrhoea and elec- ataxia, convul-
and vomiting trolyte imbalance sion, coma
Duration – 1 day to 1 week 2–7 weeks 5–15 days 1–6 h
Mortality – – 1/2 100% 100%

Chronic Effects of Radiation
Result from damage to the genetic material in dividing cells, causing abnormalities of
cell growth, such as cancer. Damage to reproductive cells has been shown to lead to
birth defects. External radiation therapy for cancer may cause nausea, vomiting and
loss of appetite, skin changes including hair loss, redness, peeling, sores, thinning of
the skin, dilated blood vessels just beneath the skin’s surface (spider veins) and skin
cancer. Radiation to the lungs can cause radiation pneumonitis and fibrosis. Radiation
to GIT may cause ulcers, fibrosis, strictures and cancer. Testes and ovaries show
tubular atrophy and stromal fibrosis, respectively, and CNS may show necrosis, gliosis
and cancer.

Q. Write briefly about exogenous oestrogens and their effects.

Ans. Oestrogen is extensively used in:
1. Menopausal hormone therapy (MHT):
(a) Given to postmenopausal women to prevent progression of osteoporosis, distress-
ing menopausal symptoms like hot flushes and reduce the likelihood of myocardial
infarction (protective role of MHT in myocardial infarction has been demonstrated
only in women under the age of 60 years; no protection in women who start MHT
after 60 years is seen).
(b) Unopposed oestrogen therapy increases the risk of endometrial cancer; risk is
reduced or eliminated when progestins are added.
(c) MHT may cause an increase in risk of breast carcinoma after a median time of
5–6 years (risk of breast carcinoma is marginally reduced with oestrogen-only
therapy in females who have undergone hysterectomy).
(d) MHT increases the risk of venous thromboembolism (deep vein thrombosis,
pulmonary embolism and stroke) by about twofold.
2. Oral contraceptives (OCs)
(a) Usually contain a synthetic oestradiol and a variable amount of progestin;
few preparations contain progesterone only. OCs inhibit ovulation and prevent
implantation.
(b) Current prevailing opinion is that OCs do not cause an increase in breast cancer
risk.
(c) OCs have a protective role in endometrial and ovarian cancer.
(d) May increase risk of cervical carcinoma in women infected with HPV virus
(increased risk may be due to increased sexual activity).
(e) Increase risk of thromboembolism. OCs induce a hypercoagulable state as they
increase hepatic synthesis of coagulation factors.
(f) Risk of cardiovascular disease increases in women over 35 years who are
smokers.
(g) Well-defined association between the use of OCs and hepatic adenoma.

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