query: #added before 2016-10
  SELECT ?politician ?cause ?politician_label ?cause_of_death_label
  WHERE
  {
  	?politician wdt:P106 wd:Q82955 .    # find items that have "occupation (P106): politician (Q82955)"
  	?politician wdt:P509 ?cause .       # with a P509 (cause of death) claim
  	?cause wdt:P279* wd:Q12078 .        # ... where the cause is a subclass of (P279*) cancer (Q12078)
  	# ?politician wdt:P39 wd:Q11696 .   # Uncomment this line to include only U.S. Presidents
  	 
  	OPTIONAL {?politician rdfs:label ?politician_label filter (lang(?politician_label) = "en") .}
  	OPTIONAL {?cause rdfs:label ?cause_of_death_label filter (lang(?cause_of_death_label) = "en").}
  }
  ORDER BY ASC (?politician)