Low power interstitial hyperthermia in the treatment of ductal carcinoma of the pancreas; an experimental study with Syrian golden hamsters

The aim of this experimental work was to study the effect of low power interstitial hyperthermia (ILH) with special emphasis on pancreatic microvasculature. This was accomplished using ductal carcinoma induced in Syrian golden hamsters as the experimental model. The animals were divided into four groups. Ten animals served as normal controls. Ductal adenocarcinoma was induced in 31 animals by subcutaneous injections of carcinogen. Ten of the tumour bearing animals served as tumour controls. There were two laser treatment groups: microangiography 1h after laser treatment and microangiography after 24h. Four months following the completion of carcinogen injection a laparotomy was conducted on each animal. Low power ILH (1W, 300s Nd-YAG laser) was used with a frosted sapphire probe. One hour after the laser treatment, the mean diameter (±SE) of tumour destruction was 2.1 (±1.00) mm which increased to 4.0 (±1.45) mm 24h after laser treatment. The demarcation area between viable and non-viable pancreatic or tumour tissue was infiltrated by leucocytes. In the microangiography, capillaries were unfilled with contrast material conforming to the histological picture of tissue destruction. However, on further examination the arterioles were filled with contrast material in the periphery of tumours whereas the central tissue area was necrotic with unfilled capillaries. Twenty-four hours from laser treatment most of arterioles in the margin of tumour necrosis were unfilled and the amount of tumour destruction was increased. It seems that tissue destruction caused by low power ILH increases during the first 24h due to both thermal and ischaemic vascular damage.