Question

14. If cancer cells from breast cancer enter the lymphatics of the breast, where are they likely to lodge and start new growths? Explain why, using your knowledge of the anatomy of the lymphatic and circulatory systems.

19. Explain why lymphedema may occur after breast surgery.

5. What is the function of interferon?

14. What are cytokines? Lymphotoxins?

10. Briefly, what role, if any, does each of the following hormones play when the body id subjected to stress: ACTH, ADH, aldosterone, cortisol, CRH, epinephrine, and norepinephrine?

Answer 1

14) About 90% of lymphatic drainage of the breast is into the axillary group of lymph nodes. This involves a group of 5 sets of lymph nodes around the axillary region. It inclused the apical, lateral, anterior, posterior and central lymph nodes. The rest 10% drains into the internal mammary lymph nodes. Some lymph also reaches other nodes such as the supraclavicular, cephalic, subperitoneal nodes,etc. Metastasis of tumor cells may take place to any of of these nodes via the lymphatics and may get seeded at these sites. Secondary tumor growth may occur in any of these lymph nodes.

19) When the lymphatics of the breast are disrupted, this results in accumulation of lymph amd hence edema results. The lymphatics may be blocked during surgical resection of the lesion or during biopsy and also in case the lesion extends to the lymphatics. The characteristic lymphedema of the breast is called 'Peau d'orange' appearance which is similar to the peel of an orange. There is puckering and dimpling of the skin over the breast. Retraction of the nipple may also be seen.

5) Interferons are chemical substances produced by the T cells and NK cells. They are chemical mediators of inflammation which perform the following functions- (a) activates macrophages and Natural Killer cells (b) stimulates B lymphocytes to secrete immunoglobulin (c) play a major role in the differentiation of T helper cells.

14) Cytokines are chemical mediators of inflammation produced by activated lymphocytes (lymphokines) and monocytes (monokines). The major cytokines are interleukins (IL-1, IL-6, IL-8, IL-12, IL-17) , Tumor Necrosis Factors (TNF a and b), Interferons and other chemokines. The function of these chemicals are to mediate the process of inflammation, by activation of lymphocytes and macrophages release of histamine, production of acute phase proteins and attracting various inflammatory cells to the site of injury.

Lymphotoxin belong to the class of Tumor Necrosis Factors (TNF-b) which are cytotoxic substances. It is formed by the B and T lymphocytes.It can target all cells of the body except the RBCs. Its function is to promote the destruction of tumor cells.

10) The response of the body when subjected to stress is mediated by a number of hormones. The pituitary gland releases ACTH which stimulates the adrenal gland to release the steroid hormone cortisol. ADH or antidiuretic hormone is also released by the pituitary. This hormone helps to reduce the urinary output by promoting reabsorption of water from the kidney tubules. Aldosterone maintains the salt and water balance of the body by regulating its excretion and reabsorption from the kidney tubules. Cortisol is the primary stress hormone, it increases circulating glucose levels to meet the increased energy demands, maintains water and electrolyte balance and brings about the fight or flight response. There is increased blood circulation to brain and skeletal muscles, decreased metabolic activities and inhibition of responses that may hinder the fight or flight situation. CRH or Corticotropin Releasing Hormone, is releaesd by the hypothalamus in stress. This is a releasing hormone that stimulates the pituitary to secrete ACTH. Epinephrine (adrenaline) and norepinephrine (noradrenaline) are relaesed from the adrenal medulla in response to stress. These hormones increase cardiac output and elevate blood pressure. The blood glucose levels also increases to cope with the figh or flight response.