See HTML::TableExtract for extracting tables from HTML.

But you don't want that here because:

• The table you want (as seen in the source of the page you linked to) is on the page at https://cancer.sanger.ac.uk/cosmic/help/census#abbrev
• The table is not in fact an HTML table but rendered as a table with:

        <h3 class="emboldened">Cancer Gene Census - Abbreviations</h3>
  
        <h4> Glossary Terms </h4>
  
        <dt class="l30">A</dt><dd class="l50"> Amplification; </dd>
        <dt class="l30">AEL</dt><dd class="l50"> Acute eosinophilic leuk
  +emia; </dd>
        <dt class="l30">AL</dt><dd class="l50"> Acute leukemia;</dd>
        <dt class="l30">ALCL</dt><dd class="l50"> Anaplastic large-cell 
  +lymphoma; </dd>
        <dt class="l30">ALL</dt><dd class="l50"> Acute lymphocytic leuke
  +mia;</dd>
  
        ...
  [download]

Please note the copyright restriction included on the page(s) you referenced. Hope this helps!