. ▁It ▁has ▁been ▁stated ▁by ▁de ▁Miguel ▁et ▁al ., ▁that ▁an ▁annual ▁three - week ▁out pat ient ▁course ▁of ▁Go e ck erman ▁treatment ▁costs ▁$ 1 0 , 0 0 0 ▁to ▁ 1 2 , 0 0 0 ▁but ▁repeat ▁treatment ▁may ▁be ▁extended ▁to ▁two ▁years ▁with ▁the ▁use ▁of ▁a ▁$ 2 , 0 0 0 ▁home ▁U VB ▁treatment ▁lamp . ▁The ▁authors ▁state ▁that ▁bi olog ic ▁ther apy ▁costs ▁$ 2 2 , 0 0 0 ▁to ▁ 5 9 , 0 0 0 ▁per ▁year . ▁ ▁Saf ety ▁Go e ck erman ▁reg im ens ▁use ▁cru de ▁coal ▁tar , ▁which ▁contains ▁poly cyc lic ▁a rom atic ▁hydro car bon , ▁a ▁car cin ogen . ▁However , ▁Go e ck erman ▁ther apy ▁is ▁considered ▁safe ▁although ▁use ▁of ▁tar ▁may ▁have ▁the ▁side - effect s ▁of ▁contact ▁der mat itis ▁and ▁m ild ▁local ▁burning ▁due ▁to ▁tar ▁hyp ers ens itivity . ▁A ▁ret ros pective ▁study ▁by ▁Stern ▁et ▁al ., ▁of ▁ 1 , 3 7 3 ▁patients ▁concluded ▁that ▁there ▁was ▁an ▁increase ▁in ▁skin ▁can cers ▁in ▁those ▁receiving ▁repeated ▁Go e ck erman ▁treat ments ▁compared ▁to ▁the ▁control ▁group . ▁This ▁has ▁been ▁ref uted ▁by ▁other ▁authors , ▁including ▁P ittel kow ▁et ▁al ., ▁who ▁state ▁there ▁has ▁not ▁been ▁an ▁increase ▁in ▁skin ▁can cers ▁among ▁those ▁treated ▁compared ▁to ▁the ▁general ▁population ▁and ▁M enter