OBJECTIVE The incidence and long-term survival analysis for vulvar cancer, due to its rarity, has not been fully described in Asian population. The objective of the study is to determine the trends in incidence and long-term survival for vulvar cancer in a Japanese population, using a population-based cancer registry data in Osaka, Japan. METHODS The age-standardized incidence rate of 389 cases of vulvar squamous cell carcinoma (SCC) diagnosed between 1976 and 2010 was calculated, using the 1985 model population of Japan. The annual percentage change (APC) of the age-standardized incidence was estimated by the joinpoint regression models. The 5- and 10-year relative survival of 290 cases with vulvar SCC diagnosed between 1976 and 2008 were analyzed, using a cohort or period approach. Using the 10-year relative survival, the conditional 5-year survival for patients who lived for some years after diagnosis was also calculated. RESULTS We have found that the age-standardized incidence rate for vulvar cancer trended downward during the period of 1979-1992 (APC - 6.3%; 95% confidence interval (CI) [- 11.3% to - 1.0%]), whereas it trended upward from 1993 to 2010 (APC 1.9%; 95% CI [- 0.7% to 4.6%]). There was no statistically significant difference for the 5- and 10-year relative survival between the two periods of 1976-2000 and 2001-2008. A statistically significant increase in the conditional 5-year survival at 2 years after diagnosis was observed (48.4%; 95% CI [41.1-55.3] versus 75.6%; 95% CI [64.0-83.9]). CONCLUSION Despite an increasing trend in vulvar cancer incidence among Japanese population, the relative survival rate for vulvar cancer did not change over the 35 years of this study. We found that the conditional 5-year survival for vulvar cancer, as patients survived additional years, approached within reach of 100%. These data can provide valuable information for both patients and clinicians.

中文翻译：

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日本女性外阴癌的发病率和长期生存趋势：基于人群的分析。

目的由于其罕见性，外阴癌的发病率和长期生存分析尚未在亚洲人群中得到充分描述。该研究的目的是使用日本大阪市基于人群的癌症登记数据来确定日本人群外阴癌的发病率和长期生存趋势。方法采用日本1985年模型人群，计算1976年至2010年间诊断的389例外阴鳞状细胞癌（SCC）的年龄标准化发病率。年龄标准化发生率的年百分比变化（APC）通过联合回归模型进行估算。使用队列或分期方法，分析了1976年至2008年之间诊断为290例外阴SCC的5年和10年相对存活率。使用10年的相对生存率，还计算了诊断后存活数年的患者有条件的5年生存率。结果我们发现外阴癌的年龄标准化发病率在1979-1992年期间呈下降趋势（APC-6.3％; 95％置信区间（CI）[-11.3％至-1.0％]），而呈趋势从1993年到2010年上升（APC 1.9％； 95％CI [-0.7％至4.6％]）。1976-2000年和2001-2008年这两个时期的5年和10年相对存活率无统计学差异。观察到诊断后2年的条件5年生存率有统计学意义的增加（48.4％； 95％CI [41.1-55.3]，而75.6％； 95％CI [64.0-83.9]）。结论尽管日本人群中外阴癌的发病率呈上升趋势，在这项研究的35年中，外阴癌的相对生存率没有变化。我们发现外阴癌的条件性5年生存期（患者可以再生存几年）接近100％。这些数据可以为患者和临床医生提供有价值的信息。