Well, the Lord God made this world and had plans for it; however, disease and death were never a part of them.
Suffering was introduced with sin, of human decision and disobedience, in the Garden of Eden and is now a mortal affliction every last one of us must endure. The presence of that pain does in no way mean that God is not there, or does not care for us, though. He is not the reason for pain and suffering, for the terrible things in this world. It can all be contributed to sin, of course, but there is also another force at work, conjuring and scheming further tortures for those on Earth.
As said, a great force is present in this world, and that is that of Satan, himself. Regardless of many doctrine subtleties or esoteric beliefs, the devil is very much a real entity. He is real, and he is the nemesis of God. He knows that in the end Jesus Christ will defeat him, and he cannot touch God or the Son, so he goes against the next best thing: God's beloved children, all of humanity.
Satan uses any and all means to turn people to disbelief, away from God. A primary method for this effect being that of pain. He will throw the entire planet into upheaval if it will cause doubt of God's presence to arise in a mortal heart. He is waging war on God, through us. His arsenal comprised of cancer, AIDS, murder, rape, starvation, drought, flood, stillbirth, and an imagination more of atrocities.
Don't be mistaken and think that God sits idly by while Satan wreaks havoc throughout the world, because He certainly does not. While all is being loosed upon Earth, God will take what Satan intends for evil and destruction, and He will make good come of it. Satan would boil all the oceans to turn one person away from God; well, God would suffer the masses sorrow if it will bring one person to His love, and to repentance. Everything Satan throws at us, God takes and turns into something beneficial.
God is willing to do anything needed to get people to return to Him. Just as a father punishing a child, it may hurt Him to watch us go through what we may, but He knows that it is for our greater good, and will let us endure it.
While the process of punishment or suffering is always going to be difficult, if just one person returns/comes to God, it is surely a cause to rejoice.
