Cigarette smoking is believed by most researchers in the field to be an important cause in the development of lung cancer and throat cancer and is believed to have much to do with some other kinds of cancers

参考译文：吸烟被该领域的大多数研究者认为是肺癌和喉癌发展的一个重要原因，并被认为与其他癌症有很大关系。

have much to do with 与…很有关系，与…有很大关系

Terminology motivations have much to do with modes of naming in respect to structure and meaning.  

术语的理据性与术语模式密切相关,后者包括结构模式和语义模式两方面的内容.

Hormones have much to do with the way the Body uses the foodstuffs offered to it.  

激素同人体怎样利用它得到的养分有很大的关系.

(1)have some to do with sth 与..有关系 

Some disgusting sugary drink pretending to have something to do with fruits of the forest? 

或者来些天然水果味,让人恶心的含糖饮料?

(2)have much to do with sth 与...有很大关系

Hormones have much to do with the way the Body uses the foodstuffs offered to it.  

激素同人体怎样利用它得到的养分有很大的关系.

(3)have nothing to do with sth 与…没关系; 

Jack would have nothing to do with such capers.  

杰克不愿扯上这种荒唐的事。

House prices are easily upset by factors which have nothing to do with property.  

房价很容易受到与房产毫不相干的因素的干扰。

develop除了”发展“，还有”发生“的意思。既可以表示从小到大的过程，也可以表示从无到有的过程。因此，名词development在这里不应翻译为癌症的”发展“，而应该是癌症的发生”。