Can­cer af­fect­ing lym­pho­cytes in the lym­phatic sys­tem is termed lym­phoma. Can­cer of lym­pho­cytes in blood be­haves some­what dif­fer­ently and is termed lym­phoid leukaemia of which also there are dif­fer­ent types

The Gulf Today - Time Out - - TRAVEL - Dr Asheesh Me­hta In­ter­nal Medicine Spe­cial­ist

Lym­phoma is a type of can­cer af­fect­ing lym­pho­cytes which are im­por­tant cells of the im­mune sys­tem. Lym­pho­cytes in the lym­phatic sys­tem are pri­mar­ily in­volved in lym­phoma, the lym­phatic sys­tem form­ing a crit­i­cal part of the im­mune sys­tem. The lym­phatic sys­tem con­sists of a net­work of channels car­ry­ing a fluid called lymph from the limbs and other or­gans towards the heart. The channels join to form lym­phatic ducts which drain into one of the larger veins in the chest. Lym­phoid tis­sue con­sist­ing of lym­pho­cytes and other im­mune cells along with con­nec­tive tis­sue is lo­cated along the lymph channels. Ag­gre­ga­tions of lym­phoid tis­sue form lymph nodes and these are scat­tered in many parts of the body in­clud­ing the neck, the in­guinal re­gion in the groin area, the armpit, in the ab­domen and chest. The ton­sils in our throat and ade­noids lo­cated be­hind the nasal pas­sages are also lymph nodes. Lym­pho­cytes serve im­por­tant im­mune func­tions with the two main types of lym­pho­cytes be­ing the B and the T lym­pho­cytes. B lym­pho­cytes pro­duce im­muno­log­i­cally ac­tive pro­teins that are called an­ti­bod­ies in re­sponse to for­eign par­ti­cles which are termed anti­gens. T lym­pho­cytes on the other hand have the ca­pa­bil­ity to at­tack anti­gens di­rectly. They also mod­u­late the ac­tiv­ity and func­tions of the im­mune sys­tem. Both B and T lym­pho­cytes have dif­fer­ent sub-types. Lym­pho­cytes are also present in blood in large num­bers, be­ing one of the types of white blood cells.

Can­cer af­fect­ing lym­pho­cytes in the lym­phatic sys­tem is termed lym­phoma. Can­cer of lym­pho­cytes in blood be­haves some­what dif­fer­ently and is termed lym­phoid leukaemia of which also there are dif­fer­ent types. In lym­phoid leukaemias blood and bone mar­row are pri­mar­ily in­volved while in lym­phomas the pri­mary in­volve­ment is of lym­phoid tis­sues in­clud­ing lymph nodes and spleen. Can­cer refers to un­reg­u­lated divi­sion of ab­nor­mal cells and in lym­phoma too this is the case. The large num­ber of ab­nor­mal cells re­sults in for­ma­tion of a mass in the af­fected lymph node or other or­gan such as the spleen. Cancer­ous lym­pho­cytes usu­ally spread to other lymph nodes via lymph channels. How­ever, spread is not re­stricted to the lym­phatic sys­tem and other or­gans too be­come sites of lym­phoma de­posits. Lym­phoma spread to or­gans other than lymph nodes are termed ex­tra­n­odal de­posits. There are many dif­fer­ent types of lym­phoma with one type given the name of Hodgkin’s lym­phoma (HL) and all the other types com­ing un­der the group head­ing of nonHodgkin’s lym­phoma (NHL). Clin­i­cal pre­sen­ta­tion of all types of lym­phomas is fairly sim­i­lar with al­most iden­ti­cal symp­toms and signs mak­ing dif­fer­en­ti­a­tion of HL from NHL on clin­i­cal grounds alone al­most im­pos­si­ble. The dif­fer­en­ti­a­tion is on the ba­sis of mi­cro­scopic find­ings of a biopsy spec­i­men. This read­ily de­ter­mines the type of lym­phoma. Hodgkin’s lym­phoma arises from an ab­nor­mal B lym­pho­cyte line of cells while NHL may arise from ei­ther an ab­nor­mal B or T cell line. Even in HL, five dif­fer­ent types are de­scribed de­pend­ing on spe­cific find­ings at mi­croscopy. Re­gard­ing NHL the char­ac­ter­is­tics vary quite a bit among dif­fer­ent types and about 30 sub-types have been iden­ti­fied. It is im­por­tant to iden­tify the type and sub-type of a lym­phoma since the treat­ment and prog­no­sis of HL and NHL and also of the var­i­ous sub-types varies quite a bit. Lym­phoma is one of the com­moner types of can­cer and usu­ally finds it­self in the top 10 adult can­cers in most coun­tries while in chil­dren it is usu­ally amongst the top 5 can­cers. NHL is much com­moner than Hodgkin’s. While lym­phomas oc­cur at all ages, HL has two peaks of in­creased fre­quency – one from about 15 years of age till the mid­dle of the fourth decade and the other peak in peo­ple older than 55 years of age. NHL is com­moner in older peo­ple.

Although a num­ber of fac­tors have been as­so­ci­ated with an in­creased risk of lym­phoma de­vel­op­ment, the ex­act cause is not de­ter­minable in most cases. In com­mon with many can­cers, in­creas­ing age is one such risk fac­tor es­pe­cially in the case of NHL. An­other im­por­tant risk fac­tor is the in­creased in­ci­dence of lym­phoma in peo­ple with cer­tain types of in­fec­tions. Ep­stein Barr virus (EBV) causes a rel­a­tively com­mon in­fec­tion called in­fec­tious mononu­cle­o­sis. The virus may per­sist in the body and its pres­ence is be­lieved to con­trib­ute to de­vel­op­ment of lym­phoma in a few in­di­vid­u­als. How­ever, lym­phoma does not de­velop in the ma­jor­ity of in­di­vid­u­als har­bour­ing this virus. Chronic iIn­fec­tion with hepati­tis B virus or hepati­tis C virus is also found to in­crease the in­ci­dence of lym­phoma de­vel­op­ment. These viruses are re­spon­si­ble for hepati­tis B and hepati­tis C re­spec­tively and much more com­monly they are as­so­ci­ated with the de­vel­op­ment of liver can­cer.­lori is a bac­terium col­o­niz­ing the up­per part of the gas­troin­testi­nal tract and re­spon­si­ble for most cases of ul­cers in the stom­ach and duo­de­num. Many dif­fer­ent dis­eases in­clud­ing in­creased in­ci­dence of stom­ach can­cer, is­chaemic heart dis­ease and lym­phoma have been at­trib­uted to this bac­terium at some time or the other. Lym­phoma is also much com­moner in peo­ple with com­pro­mised im­mu­nity. The poor im­mu­nity al­lows dis­eased cells to sur­vive. A lead­ing cause of low­ered im­mu­nity is HIV in­fec­tion. Use of drugs to sup­press im­mu­nity, com­monly used after or­gan trans­plant is an­other very im­por­tant cause. Low­ered im­mu­nity is also a char­ac­ter­is­tic of a num­ber of other in­her­ited as well as ac­quired dis­eases. Ex­po­sure to nox­ious chem­i­cals is an­other im­por­tant cause of lym­phoma. Var­i­ous in­dus­trial chem­i­cals, pes­ti­cides, in­sec­ti­cides, etc have been im­pli­cated. Ra­di­a­tion ex­po­sure as may oc­cur dur­ing a nu­clear ac­ci­dent or dur­ing ra­dio­ther­apy can­cer is an­other well known cause.

Symp­toms are fairly sim­i­lar in most types of lym­phoma. En­large­ment of lymph nodes is ev­i­dent as swellings most usu­ally de­tectable in the neck, armpit and groin ar­eas. It needs to be re­mem­bered that lym­phoma is only one of the quite long list of causes in which lymph node en­large­ment oc­curs. In lym­phoma the nodes are usu­ally pain­less. The spleen which is lo­cated in the left up­per ab­domen may also en­large and this may some­times be painful. Deeply si­t­u­ated lymph nodes as in the chest and ab­domen are also en­larged and may cause symp­toms by com­press­ing sur­round­ing struc­tures. Sys­temic symp­toms oc­cur in a pro­por­tion of pa­tients and in­clude pro­longed fever with or with­out chills, night sweats, weight loss, poor ap­petite, un­ex­plained itch­ing, un­usual fa­tigue, etc. Most of these symp­toms also oc­cur in a num­ber of in­fec­tions and hence while the di­ag­no­sis of lym­phoma may be sus­pected from these in­d­ings fur­ther tests are needed for conir­ma­tion of di­ag­no­sis.

The deini­tive test for di­ag­no­sis is mi­cro­scopic ex­am­i­na­tion of tis­sue ob­tained at biopsy. Nee­dle biopsy is less trau­matic and more eas­ily car­ried out but in­ter­pre­ta­tion is more di­fi­cult and also false neg­a­tive is more fre­quent. Sur­gi­cal biopsy of en­larged lymph nodes, if read­ily ac­ces­si­ble, is a good method of ob­tain­ing ad­e­quate tis­sue. When only lymph nodes in the chest or ab­domen are en­larged a biopsy is car­ried out by in­sert­ing an en­do­scope through a small in­ci­sion. Bone mar­row biopsy can also be car­ried out on out-pa­tient ba­sis and is also of­ten quite help­ful. Var­i­ous imag­ing tech­niques such as ul­tra­sound, x-ray, CT scan, etc also de­tect en­larged lymph nodes or in­volve­ment of other or­gans. Blood tests are also re­quired. On the ba­sis of the var­i­ous tests grad­ing and stag­ing of the lym­phoma are done. Grad­ing refers to how well the lym­phoma cells re­tain char­ac­ter­is­tics of the orig­i­nal cells. Poorly dif­fer­en­ti­ated cells are de­noted by a higher grad­ing and sug­gest a more ag­gres­sive lym­phoma. Stag­ing gives an idea of the de­gree of spread of the lym­phoma, higher stag­ing mean­ing greater spread and poorer prog­no­sis.

Var­i­ous types of treat­ment modal­i­ties are avail­able to treat lym­phoma. The con­ven­tional ones are ra­dio­ther­apy and chemo­ther­apy. Very of­ten both are given in com­bi­na­tion. Both are as­so­ci­ated with sig­ni­icant tox­i­c­ity which can be ame­lio­rated to a sig­ni­icant de­gree by us­ing ju­di­cious doses and by giv­ing other medicines to re­duce side ef­fects such as nau­sea. Chemo­ther­apy is usu­ally given as com­bi­na­tion of mul­ti­ple drugs and in cy­cles with drug-free pe­ri­ods in be­tween cy­cles. Dif­fer­ent drug pro­to­cols are ad­vised for dif­fer­ent types of lym­phomas and even for the same type of lym­phoma the pro­to­col may vary de­pend­ing on fac­tors such as the age of the pa­tient, the type and sub-type of lym­phoma, the stage and grade of the can­cer, etc. Dif­fer­ing drug pro­to­cols may also be adopted by dif­fer­ent treat­ment cen­tres. Also, de­pend­ing on the in­tro­duc­tion of new medicines as well as chang­ing re­sponses to ther­apy, newer pro­to­cols are rec­om­mended from time to time. A third op­tion is im­munother­apy usu­ally in the form of mon­o­clonal an­ti­body or cy­tokines. These are less fre­quently used but have shown ex­cel­lent re­sults in se­lected pa­tients.

Com­pared to most other can­cers, lym­phoma has a much bet­ter prog­no­sis. In gen­eral HL re­sponds bet­ter to treat­ment than NHL. The 5 year sur­vival rates for HL are above 80% and 90% in adults and chil­dren re­spec­tively while for NHL this is above 60% and above 85% for adults and chil­dren re­spec­tively.

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