Detection of clinically insignificant prostate cancer by allelic imbalance analysis

临床上无意义的前列腺癌的标准肿瘤体积（TV）已有报道，但不同研究之间存在差异：一些研究报告TV < 200 mm^3 ;另一些研究报告TV <500 mm^3。本研究的目的是使用分子生物学方法区分临床上不重要的癌症和重要的癌症。选择了总共184个限定在3 mm圆内的显微镜下癌症（MC）和82个主要肿瘤（MT）结节。在6 q22、8p23.2-23、13 q14和13 q33共13个微卫星位点进行杂合性丢失（洛）分析。MT分为TV <500 mm^3或> 500 mm^3、TV < 200 mm^3或> 200 mm^3、TV < 200 mm^3或200 mm^3、TV < 500 mm^3或> 500 mm^3三组，比较三组间洛缺失的发生率。6 q16 -21、6 q22、8p23.1、8p23.2、13 q14位点的洛缺失率在MC中分别为1.0%、2.7%、1.9%、1.1%和5.4%，显著低于MT中的30.9%、40.4%、12%、8.7%和20.6%。在这些TV设置中没有发现洛频率的显著差异。当不显著的肿瘤定义为TV < 200 mm^3或< 500 mm^3时，它应包括具有与较大肿瘤相当的恶性潜能的肿瘤。建议在严格的安全范围内，将TV设置得较低，以识别不重要的肿瘤。

The criterion tumor volume (TV) for clinically insignificant prostate cancer has been reported, but it differs from study to study : some have reported TV < 200 mm^3 ; others, <500 mm^3. The aim of the present study was to distinguish clinically insignificant cancers from significant ones using molecular biological methods. A total of 184 microscopic cancers (MC) defined as limited within a 3 mm circle and 82 main tumor (MT) nodules were selected. Thirteen microsatellite loci at 6q22, 8p23.2-23, 13q14 and 13q33 were evaluated for loss of heterozygosity (LOH). MT were subgrouped as TV <500 mm^3 or > 500 mm^3 ; TV < 200 mm^3 or > 200 mm^3 ; and TV < 200 mm^3 or 200 mm^3 〓 TV < 500 mm^3 or〓500 mm^3 ; and frequencies of LOH were compared between these three groups. Frequencies of LOH at 6q16-21, 6q22, 8p23.1, 8p23.2, 13q14 were significantly lower in MC (1.0%, 2.7%, 1.9%, 1.1% and 5.4%) than in MT (30.9%, 40.4%, 12%, 8.7% and 20.6%). No significant differences in LOH frequencies were found at any of these TV settings. When insignificant tumor is defined as TV < 200 mm^3 or < 500 mm^3, it should include tumors with malignant potential equivalent to larger tumors. It is suggested that in order to identify insignificant tumor within a strict safety range, TV should be set lower.